diff --git a/doc b/doc
index 0cf3d59..411880a 160000
--- a/doc
+++ b/doc
@@ -1 +1 @@
-Subproject commit 0cf3d59c8b37f84e915f5e30e7447f0611cc1238
+Subproject commit 411880ae72b3a2204fed4b945bdb3a15d3ece364
diff --git a/matemat/db/facade.py b/matemat/db/facade.py
index 5e8fffc..ec44ac9 100644
--- a/matemat/db/facade.py
+++ b/matemat/db/facade.py
@@ -4,11 +4,14 @@ from typing import List, Optional, Any, Type
 
 import crypt
 from hmac import compare_digest
+from datetime import datetime
+import logging
 
-from matemat.db.primitives import User, Product
+from matemat.db.primitives import User, Product, ReceiptPreference, Receipt,\
+    Transaction, Consumption, Deposit, Modification
 from matemat.exceptions import AuthenticationError, DatabaseConsistencyError
 from matemat.db import DatabaseWrapper
-from matemat.db.wrapper import Transaction
+from matemat.db.wrapper import DatabaseTransaction
 
 
 class MatematDatabase(object):
@@ -46,7 +49,7 @@ class MatematDatabase(object):
         # Pass context manager stuff through to the database wrapper
         self.db.__exit__(exc_type, exc_val, exc_tb)
 
-    def transaction(self, exclusive: bool = True) -> Transaction:
+    def transaction(self, exclusive: bool = True) -> DatabaseTransaction:
         """
         Begin a new SQLite3 transaction (exclusive by default).  You should never need to use the returned object (a
         Transaction instance).  It is provided in case there is a real need for it (e.g. for unit testing).
@@ -83,15 +86,19 @@ class MatematDatabase(object):
         users: List[User] = []
         with self.db.transaction(exclusive=False) as c:
             for row in c.execute('''
-                SELECT user_id, username, email, is_admin, is_member, balance
+                SELECT user_id, username, email, is_admin, is_member, balance, receipt_pref
                 FROM users
                 WHERE touchkey IS NOT NULL OR NOT :must_have_touchkey
               ''', {
                 'must_have_touchkey': with_touchkey
             }):
                 # Decompose each row and put the values into a User object
-                user_id, username, email, is_admin, is_member, balance = row
-                users.append(User(user_id, username, balance, email, is_admin, is_member))
+                user_id, username, email, is_admin, is_member, balance, receipt_p = row
+                try:
+                    receipt_pref: ReceiptPreference = ReceiptPreference(receipt_p)
+                except ValueError:
+                    raise DatabaseConsistencyError(f'{receipt_p} is not a valid ReceiptPreference')
+                users.append(User(user_id, username, balance, email, is_admin, is_member, receipt_pref))
         return users
 
     def get_user(self, uid: int) -> User:
@@ -101,14 +108,22 @@ class MatematDatabase(object):
         """
         with self.db.transaction(exclusive=False) as c:
             # Fetch all values to construct the user
-            c.execute('SELECT user_id, username, email, is_admin, is_member, balance FROM users WHERE user_id = ?',
+            c.execute('''
+                SELECT user_id, username, email, is_admin, is_member, balance, receipt_pref
+                FROM users
+                WHERE user_id = ?
+                ''',
                       [uid])
             row = c.fetchone()
             if row is None:
                 raise ValueError(f'No user with user ID {uid} exists.')
             # Unpack the row and construct the user
-            user_id, username, email, is_admin, is_member, balance = row
-            return User(user_id, username, balance, email, is_admin, is_member)
+            user_id, username, email, is_admin, is_member, balance, receipt_p = row
+            try:
+                receipt_pref: ReceiptPreference = ReceiptPreference(receipt_p)
+            except ValueError:
+                raise DatabaseConsistencyError(f'{receipt_p} is not a valid ReceiptPreference')
+            return User(user_id, username, balance, email, is_admin, is_member, receipt_pref)
 
     def create_user(self,
                     username: str,
@@ -136,8 +151,8 @@ class MatematDatabase(object):
                 raise ValueError(f'A user with the name \'{username}\' already exists.')
             # Insert the user into the database.
             c.execute('''
-              INSERT INTO users (username, email, password, balance, is_admin, is_member, lastchange)
-              VALUES (:username, :email, :pwhash, 0, :admin, :member, STRFTIME('%s', 'now'))
+              INSERT INTO users (username, email, password, balance, is_admin, is_member, lastchange, created)
+              VALUES (:username, :email, :pwhash, 0, :admin, :member, STRFTIME('%s', 'now'), STRFTIME('%s', 'now'))
             ''', {
                 'username': username,
                 'email': email,
@@ -165,14 +180,14 @@ class MatematDatabase(object):
             raise ValueError('Exactly one of password and touchkey must be provided')
         with self.db.transaction(exclusive=False) as c:
             c.execute('''
-              SELECT user_id, username, email, password, touchkey, is_admin, is_member, balance
+              SELECT user_id, username, email, password, touchkey, is_admin, is_member, balance, receipt_pref
               FROM users
               WHERE username = ?
               ''', [username])
             row = c.fetchone()
             if row is None:
                 raise AuthenticationError('User does not exist')
-            user_id, username, email, pwhash, tkhash, admin, member, balance = row
+            user_id, username, email, pwhash, tkhash, admin, member, balance, receipt_p = row
             if password is not None and not compare_digest(crypt.crypt(password, pwhash), pwhash):
                 raise AuthenticationError('Password mismatch')
             elif touchkey is not None \
@@ -181,7 +196,11 @@ class MatematDatabase(object):
                 raise AuthenticationError('Touchkey mismatch')
             elif touchkey is not None and tkhash is None:
                 raise AuthenticationError('Touchkey not set')
-            return User(user_id, username, balance, email, admin, member)
+            try:
+                receipt_pref: ReceiptPreference = ReceiptPreference(receipt_p)
+            except ValueError:
+                raise DatabaseConsistencyError(f'{receipt_p} is not a valid ReceiptPreference')
+            return User(user_id, username, balance, email, admin, member, receipt_pref)
 
     def change_password(self, user: User, oldpass: str, newpass: str, verify_password: bool = True) -> None:
         """
@@ -243,8 +262,7 @@ class MatematDatabase(object):
                 'tkhash': tkhash
             })
 
-    def change_user(self, user: User, agent: Optional[User], **kwargs)\
-            -> None:
+    def change_user(self, user: User, agent: Optional[User], **kwargs) -> None:
         """
         Commit changes to the user in the database.  If writing the requested changes succeeded, the values are updated
         in the provided user object.  Otherwise the user object is left untouched.  The user to update is identified by
@@ -258,9 +276,11 @@ class MatematDatabase(object):
         # Resolve the values to change
         name: str = kwargs['name'] if 'name' in kwargs else user.name
         email: str = kwargs['email'] if 'email' in kwargs else user.email
-        balance: int = kwargs['balance'] if 'balance' in kwargs else user.balance
         is_admin: bool = kwargs['is_admin'] if 'is_admin' in kwargs else user.is_admin
         is_member: bool = kwargs['is_member'] if 'is_member' in kwargs else user.is_member
+        balance: int = kwargs['balance'] if 'balance' in kwargs else user.balance
+        balance_reason: Optional[str] = kwargs['balance_reason'] if 'balance_reason' in kwargs else None
+        receipt_pref: ReceiptPreference = kwargs['receipt_pref'] if 'receipt_pref' in kwargs else user.receipt_pref
         with self.db.transaction() as c:
             c.execute('SELECT balance FROM users WHERE user_id = :user_id', {'user_id': user.id})
             row = c.fetchone()
@@ -278,11 +298,13 @@ class MatematDatabase(object):
                     'value': balance - oldbalance,
                     'old_balance': oldbalance
                 })
-                # TODO: Implement reason field
                 c.execute('''
-                INSERT INTO modifications (ta_id, agent_id, reason)
-                  VALUES (last_insert_rowid(), :agent_id, NULL)
-                ''', {'agent_id': agent.id})
+                INSERT INTO modifications (ta_id, agent, reason)
+                  VALUES (last_insert_rowid(), :agent, :reason)
+                ''', {
+                    'agent': agent.name,
+                    'reason': balance_reason
+                })
             c.execute('''
             UPDATE users SET
               username = :username,
@@ -290,6 +312,7 @@ class MatematDatabase(object):
               balance = :balance,
               is_admin = :is_admin,
               is_member = :is_member,
+              receipt_pref = :receipt_pref,
               lastchange = STRFTIME('%s', 'now')
             WHERE user_id = :user_id
             ''', {
@@ -298,7 +321,8 @@ class MatematDatabase(object):
                 'email': email,
                 'balance': balance,
                 'is_admin': is_admin,
-                'is_member': is_member
+                'is_member': is_member,
+                'receipt_pref': receipt_pref.value
             })
         # Only update the actual user object after the changes in the database succeeded
         user.name = name
@@ -306,6 +330,7 @@ class MatematDatabase(object):
         user.balance = balance
         user.is_admin = is_admin
         user.is_member = is_member
+        user.receipt_pref = receipt_pref
 
     def delete_user(self, user: User) -> None:
         """
@@ -460,10 +485,10 @@ class MatematDatabase(object):
                 'old_balance': user.balance
             })
             c.execute('''
-            INSERT INTO consumptions (ta_id, product_id)
-              VALUES (last_insert_rowid(), :product_id)
+            INSERT INTO consumptions (ta_id, product)
+              VALUES (last_insert_rowid(), :product)
             ''', {
-                'product_id': product.id
+                'product': product.name
             })
             # Subtract the price from the user's account balance.
             c.execute('''
@@ -491,6 +516,9 @@ class MatematDatabase(object):
             if affected != 1:
                 raise DatabaseConsistencyError(
                     f'increment_consumption should affect 1 products row, but affected {affected}')
+        # Reflect the change in the user and product objects
+        user.balance -= price
+        product.stock -= 1
 
     def restock(self, product: Product, count: int) -> None:
         """
@@ -511,6 +539,8 @@ class MatematDatabase(object):
             affected = c.execute('SELECT changes()').fetchone()[0]
             if affected != 1:
                 raise DatabaseConsistencyError(f'restock should affect 1 products row, but affected {affected}')
+        # Reflect the change in the product object
+        product.stock += count
 
     def deposit(self, user: User, amount: int) -> None:
         """
@@ -523,13 +553,19 @@ class MatematDatabase(object):
         if amount < 0:
             raise ValueError('Cannot deposit a negative value')
         with self.db.transaction() as c:
+            c.execute('''SELECT balance FROM users WHERE user_id = :user_id''',
+                      [user.id])
+            row = c.fetchone()
+            if row is None:
+                raise DatabaseConsistencyError(f'No such user: {user.id}')
+            old_balance: int = row[0]
             c.execute('''
             INSERT INTO transactions (user_id, value, old_balance)
               VALUES (:user_id, :value, :old_balance)
             ''', {
                 'user_id': user.id,
                 'value': amount,
-                'old_balance': user.balance
+                'old_balance': old_balance
             })
             c.execute('''
             INSERT INTO deposits (ta_id)
@@ -546,3 +582,84 @@ class MatematDatabase(object):
             affected = c.execute('SELECT changes()').fetchone()[0]
             if affected != 1:
                 raise DatabaseConsistencyError(f'deposit should affect 1 users row, but affected {affected}')
+        # Reflect the change in the user object
+        user.balance = old_balance + amount
+
+    def check_receipt_due(self, user: User) -> bool:
+        if not isinstance(user.receipt_pref, ReceiptPreference):
+            raise TypeError()
+        if user.receipt_pref == ReceiptPreference.NONE or user.email is None:
+            return False
+        with self.db.transaction() as c:
+            c.execute('''
+            SELECT COALESCE(MAX(r.date), u.created)
+            FROM users AS u
+            LEFT JOIN receipts AS r
+              ON r.user_id = u.user_id
+            WHERE u.user_id = :user_id
+            ''', [user.id])
+
+        last_receipt: datetime = datetime.fromtimestamp(c.fetchone()[0])
+        next_receipt_due: datetime = user.receipt_pref.next_receipt_due(last_receipt)
+        return datetime.utcnow() > next_receipt_due
+
+    def create_receipt(self, user: User, write: bool = False) -> Receipt:
+        transactions: List[Transaction] = []
+        with self.db.transaction() as cursor:
+            cursor.execute('''
+            SELECT COALESCE(MAX(r.date), u.created), COALESCE(MAX(r.last_ta_id), 0)
+            FROM users AS u
+            LEFT JOIN receipts AS r
+              ON r.user_id = u.user_id
+            WHERE u.user_id = :user_id
+            ''', [user.id])
+            row = cursor.fetchone()
+            if row is None:
+                raise DatabaseConsistencyError(f'No such user: {user.id}')
+            fromdate, min_id = row
+            created: datetime = datetime.fromtimestamp(fromdate)
+            cursor.execute('''
+            SELECT
+              t.ta_id, t.value, t.old_balance, COALESCE(t.date, 0),
+              c.ta_id, d.ta_id, m.ta_id, c.product, m.agent, m.reason
+            FROM transactions AS t
+            LEFT JOIN consumptions AS c
+              ON t.ta_id = c.ta_id
+            LEFT JOIN deposits AS d
+              ON t.ta_id = d.ta_id
+            LEFT JOIN modifications AS m
+              ON t.ta_id = m.ta_id
+            WHERE t.user_id = :user_id
+              AND t.ta_id > :min_id
+            ORDER BY t.date ASC
+            ''', {
+                'user_id': user.id,
+                'min_id': min_id
+            })
+            rows = cursor.fetchall()
+            for row in rows:
+                ta_id, value, old_balance, date, c, d, m, c_prod, m_agent, m_reason = row
+                if c == ta_id:
+                    t: Transaction = Consumption(ta_id, user, value, old_balance, datetime.fromtimestamp(date), c_prod)
+                elif d == ta_id:
+                    t = Deposit(ta_id, user, value, old_balance, datetime.fromtimestamp(date))
+                elif m == ta_id:
+                    t = Modification(ta_id, user, value, old_balance, datetime.fromtimestamp(date), m_agent, m_reason)
+                else:
+                    t = Transaction(ta_id, user, value, old_balance, datetime.fromtimestamp(date))
+                transactions.append(t)
+            if write:
+                cursor.execute('''
+                INSERT INTO receipts (user_id, first_ta_id, last_ta_id)
+                  VALUES (:user_id, :first_ta, :last_ta)
+                ''', {
+                    'user_id': user.id,
+                    'first_ta': transactions[0].id,
+                    'last_ta': transactions[-1].id
+                })
+                cursor.execute('''SELECT last_insert_rowid()''')
+                receipt_id: int = int(cursor.fetchone()[0])
+            else:
+                receipt_id = -1
+        receipt = Receipt(receipt_id, transactions, user, created, datetime.utcnow())
+        return receipt
diff --git a/matemat/db/migrations.py b/matemat/db/migrations.py
index 28274d6..8983180 100644
--- a/matemat/db/migrations.py
+++ b/matemat/db/migrations.py
@@ -113,3 +113,91 @@ def migrate_schema_1_to_2(c: sqlite3.Cursor):
                     ta_id -= 1
     # Drop the old consumption table
     c.execute('DROP TABLE consumption')
+
+
+def migrate_schema_2_to_3(c: sqlite3.Cursor):
+    # Add missing columns to users table
+    c.execute('ALTER TABLE users ADD COLUMN receipt_pref INTEGER(1) NOT NULL DEFAULT 0')
+    c.execute('''ALTER TABLE users ADD COLUMN created INTEGER(8) NOT NULL DEFAULT 0''')
+    # Guess creation date based on the oldest entry in the database related to the user ( -1 minute for good measure)
+    c.execute('''
+    UPDATE users
+      SET created = COALESCE(
+        (SELECT MIN(t.date)
+          FROM transactions AS t
+          WHERE t.user_id = users.user_id),
+        lastchange) - 60
+    ''')
+
+    # Fix ON DELETE in transactions table
+    c.execute('''
+    CREATE TABLE transactions_new (
+      ta_id INTEGER PRIMARY KEY,
+      user_id INTEGER DEFAULT NULL,
+      value INTEGER(8) NOT NULL,
+      old_balance INTEGER(8) NOT NULL,
+      date INTEGER(8) DEFAULT (STRFTIME('%s', 'now')),
+      FOREIGN KEY (user_id) REFERENCES users(user_id)
+        ON DELETE SET NULL ON UPDATE CASCADE
+    )
+    ''')
+    c.execute('INSERT INTO transactions_new SELECT * FROM transactions')
+    c.execute('DROP TABLE transactions')
+    c.execute('ALTER TABLE transactions_new RENAME TO transactions')
+
+    # Change consumptions table
+    c.execute('''
+        CREATE TABLE consumptions_new (
+          ta_id INTEGER PRIMARY KEY,
+          product TEXT NOT NULL,
+          FOREIGN KEY (ta_id) REFERENCES transactions(ta_id)
+            ON DELETE CASCADE ON UPDATE CASCADE
+        )
+        ''')
+    c.execute('''
+        INSERT INTO consumptions_new (ta_id, product)
+          SELECT c.ta_id, COALESCE(p.name, '<unknown>')
+            FROM consumptions as c
+            LEFT JOIN products as p
+              ON c.product_id = p.product_id
+        ''')
+    c.execute('DROP TABLE consumptions')
+    c.execute('ALTER TABLE consumptions_new RENAME TO consumptions')
+
+    # Change modifications table
+    c.execute('''
+    CREATE TABLE modifications_new (
+      ta_id INTEGER NOT NULL,
+      agent TEXT NOT NULL,
+      reason TEXT DEFAULT NULL,
+      PRIMARY KEY (ta_id),
+      FOREIGN KEY (ta_id) REFERENCES transactions(ta_id)
+        ON DELETE CASCADE ON UPDATE CASCADE
+    )
+    ''')
+    c.execute('''
+    INSERT INTO modifications_new (ta_id, agent, reason)
+      SELECT m.ta_id, COALESCE(u.username, '<unknown>'), m.reason
+        FROM modifications as m
+        LEFT JOIN users as u
+          ON u.user_id = m.agent_id
+    ''')
+    c.execute('DROP TABLE modifications')
+    c.execute('ALTER TABLE modifications_new RENAME TO modifications')
+
+    # Create missing table
+    c.execute('''
+    CREATE TABLE receipts (  -- receipts sent to the users
+      receipt_id INTEGER PRIMARY KEY,
+      user_id INTEGER NOT NULL,
+      first_ta_id INTEGER NOT NULL,
+      last_ta_id INTEGER NOT NULL,
+      date INTEGER(8) DEFAULT (STRFTIME('%s', 'now')),
+      FOREIGN KEY (user_id) REFERENCES users(user_id)
+        ON DELETE CASCADE ON UPDATE CASCADE,
+      FOREIGN KEY (first_ta_id) REFERENCES transactions(ta_id)
+        ON DELETE SET NULL ON UPDATE CASCADE,
+      FOREIGN KEY (last_ta_id) REFERENCES transactions(ta_id)
+        ON DELETE SET NULL ON UPDATE CASCADE
+    )
+    ''')
diff --git a/matemat/db/primitives/Receipt.py b/matemat/db/primitives/Receipt.py
new file mode 100644
index 0000000..2ddbe12
--- /dev/null
+++ b/matemat/db/primitives/Receipt.py
@@ -0,0 +1,17 @@
+
+from typing import List
+from dataclasses import dataclass
+
+from datetime import datetime
+
+from matemat.db.primitives import User, Transaction
+
+
+@dataclass
+class Receipt:
+
+    id: int
+    transactions: List[Transaction]
+    user: User
+    from_date: datetime
+    to_date: datetime
diff --git a/matemat/db/primitives/ReceiptPreference.py b/matemat/db/primitives/ReceiptPreference.py
new file mode 100644
index 0000000..fb15f18
--- /dev/null
+++ b/matemat/db/primitives/ReceiptPreference.py
@@ -0,0 +1,62 @@
+from typing import Callable
+
+from enum import Enum
+
+from datetime import datetime, timedelta
+from matemat.util.monthdelta import add_months
+
+
+class ReceiptPreference(Enum):
+    """
+    A user's preference for the frequency of receiving receipts.
+    """
+
+    def __new__(cls, *args, **kwargs):
+        e = object.__new__(cls)
+        # The enum's internal value
+        e._value_: int = args[0]
+        # The function calculating the date after which a new receipt is due.
+        e._datefunc: Callable[[datetime], datetime] = args[1]
+        # The human-readable description
+        e._human_readable: str = args[2]
+        return e
+
+    @property
+    def human_readable(self) -> str:
+        """
+        A human-readable description of the receipt preference, to be displayed in the UI.
+        """
+        return self._human_readable
+
+    def next_receipt_due(self, d: datetime) -> datetime:
+        return self._datefunc(d)
+
+    """
+    No receipts should be generated.
+    """
+    NONE = 0, (lambda d: None), 'No receipts'
+
+    """
+    A receipt should be generated once a week.
+    """
+    WEEKLY = 1, (lambda d: d + timedelta(weeks=1)), 'Weekly'
+
+    """
+    A receipt should be generated once a month.
+    """
+    MONTHLY = 2, (lambda d: add_months(d, 1)), 'Monthly'
+
+    """
+    A receipt should be generated once every three month.
+    """
+    QUARTERLY = 3, (lambda d: add_months(d, 3)), 'Quarterly'
+
+    """
+    A receipt should be generated once every six month.
+    """
+    BIANNUALLY = 4, (lambda d: add_months(d, 6)), 'Biannually'
+
+    """
+    A receipt should be generated once a year.
+    """
+    YEARLY = 5, (lambda d: add_months(d, 12)), 'Annually'
diff --git a/matemat/db/primitives/Transaction.py b/matemat/db/primitives/Transaction.py
new file mode 100644
index 0000000..964b835
--- /dev/null
+++ b/matemat/db/primitives/Transaction.py
@@ -0,0 +1,74 @@
+
+from typing import Optional
+from dataclasses import dataclass
+
+from datetime import datetime
+
+from matemat.db.primitives import User
+from matemat.util.currency_format import format_chf
+
+
+@dataclass(frozen=True)
+class Transaction:
+
+    id: int
+    user: User
+    value: int
+    old_balance: int
+    date: datetime
+
+    @property
+    def receipt_date(self) -> str:
+        if self.date == datetime.fromtimestamp(0):
+            return '<unknown>        '
+        date: str = self.date.strftime('%d.%m.%Y, %H:%M')
+        return date
+
+    @property
+    def receipt_value(self) -> str:
+        value: str = format_chf(self.value, with_currencysign=False, plus_sign=True).rjust(8)
+        return value
+
+    @property
+    def receipt_description(self) -> str:
+        return 'Unidentified transaction'
+
+    @property
+    def receipt_message(self) -> Optional[str]:
+        return None
+
+
+@dataclass(frozen=True)
+class Consumption(Transaction):
+
+    product: str
+
+    @property
+    def receipt_description(self) -> str:
+        return self.product
+
+
+@dataclass(frozen=True)
+class Deposit(Transaction):
+
+    @property
+    def receipt_description(self) -> str:
+        return 'Deposit'
+
+
+@dataclass(frozen=True)
+class Modification(Transaction):
+
+    agent: str
+    reason: Optional[str]
+
+    @property
+    def receipt_description(self) -> str:
+        return f'Balance modified by {self.agent}'
+
+    @property
+    def receipt_message(self) -> Optional[str]:
+        if self.reason is None:
+            return None
+        else:
+            return f'Reason: «{self.reason}»'
diff --git a/matemat/db/primitives/User.py b/matemat/db/primitives/User.py
index 4d2cee6..3bf25cc 100644
--- a/matemat/db/primitives/User.py
+++ b/matemat/db/primitives/User.py
@@ -2,6 +2,7 @@
 from typing import Optional
 
 from dataclasses import dataclass
+from matemat.db.primitives.ReceiptPreference import ReceiptPreference
 
 
 @dataclass
@@ -17,6 +18,7 @@ class User:
     :param email: The user's e-mail address (optional).
     :param admin: Whether the user is an administrator.
     :param member: Whether the user is a member.
+    :param receipt_pref: The user's preference on how often to receive transaction receipts.
     """
 
     id: int
@@ -25,3 +27,4 @@ class User:
     email: Optional[str] = None
     is_admin: bool = False
     is_member: bool = False
+    receipt_pref: ReceiptPreference = ReceiptPreference.NONE
diff --git a/matemat/db/primitives/__init__.py b/matemat/db/primitives/__init__.py
index a18a142..ff7e95b 100644
--- a/matemat/db/primitives/__init__.py
+++ b/matemat/db/primitives/__init__.py
@@ -4,3 +4,6 @@ This package provides the 'primitive types' the Matemat software deals with - na
 
 from .User import User
 from .Product import Product
+from .ReceiptPreference import ReceiptPreference
+from .Transaction import Transaction, Consumption, Deposit, Modification
+from .Receipt import Receipt
diff --git a/matemat/db/schemas.py b/matemat/db/schemas.py
index 5434ec1..3bbb5b9 100644
--- a/matemat/db/schemas.py
+++ b/matemat/db/schemas.py
@@ -101,3 +101,80 @@ SCHEMAS[2] = [
         ON DELETE CASCADE ON UPDATE CASCADE
     );
     ''']
+
+SCHEMAS[3] = [
+    '''
+    CREATE TABLE users (
+      user_id INTEGER PRIMARY KEY,
+      username TEXT UNIQUE NOT NULL,
+      email TEXT DEFAULT NULL,
+      password TEXT NOT NULL,
+      touchkey TEXT DEFAULT NULL,
+      is_admin INTEGER(1) NOT NULL DEFAULT 0,
+      is_member INTEGER(1) NOT NULL DEFAULT 1,
+      balance INTEGER(8) NOT NULL DEFAULT 0,
+      lastchange INTEGER(8) NOT NULL DEFAULT 0,
+      receipt_pref INTEGER(1) NOT NULL DEFAULT 0,
+      created INTEGER(8) NOT NULL DEFAULT 0
+    );
+    ''',
+    '''
+    CREATE TABLE products (
+      product_id INTEGER PRIMARY KEY,
+      name TEXT UNIQUE NOT NULL,
+      stock INTEGER(8) NOT NULL DEFAULT 0,
+      price_member INTEGER(8) NOT NULL,
+      price_non_member INTEGER(8) NOT NULL
+    );
+    ''',
+    '''
+    CREATE TABLE transactions (  -- "superclass" of the following 3 tables
+      ta_id INTEGER PRIMARY KEY,
+      user_id INTEGER DEFAULT NULL,
+      value INTEGER(8) NOT NULL,
+      old_balance INTEGER(8) NOT NULL,
+      date INTEGER(8) DEFAULT (STRFTIME('%s', 'now')),
+      FOREIGN KEY (user_id) REFERENCES users(user_id)
+        ON DELETE SET NULL ON UPDATE CASCADE
+    );
+    ''',
+    '''
+    CREATE TABLE consumptions (  -- transactions involving buying a product
+      ta_id INTEGER PRIMARY KEY,
+      product TEXT NOT NULL,
+      FOREIGN KEY (ta_id) REFERENCES transactions(ta_id)
+        ON DELETE CASCADE ON UPDATE CASCADE
+    );
+    ''',
+    '''
+    CREATE TABLE deposits (  -- transactions involving depositing cash
+      ta_id INTEGER PRIMARY KEY,
+      FOREIGN KEY (ta_id) REFERENCES transactions(ta_id)
+        ON DELETE CASCADE ON UPDATE CASCADE
+    );
+    ''',
+    '''
+    CREATE TABLE modifications (  -- transactions involving balance modification by an admin
+      ta_id INTEGER NOT NULL,
+      agent TEXT NOT NULL,
+      reason TEXT DEFAULT NULL,
+      PRIMARY KEY (ta_id),
+      FOREIGN KEY (ta_id) REFERENCES transactions(ta_id)
+        ON DELETE CASCADE ON UPDATE CASCADE
+    );
+    ''',
+    '''
+    CREATE TABLE receipts (  -- receipts sent to the users
+      receipt_id INTEGER PRIMARY KEY,
+      user_id INTEGER NOT NULL,
+      first_ta_id INTEGER NOT NULL,
+      last_ta_id INTEGER NOT NULL,
+      date INTEGER(8) DEFAULT (STRFTIME('%s', 'now')),
+      FOREIGN KEY (user_id) REFERENCES users(user_id)
+        ON DELETE CASCADE ON UPDATE CASCADE,
+      FOREIGN KEY (first_ta_id) REFERENCES transactions(ta_id)
+        ON DELETE SET NULL ON UPDATE CASCADE,
+      FOREIGN KEY (last_ta_id) REFERENCES transactions(ta_id)
+        ON DELETE SET NULL ON UPDATE CASCADE
+    );
+    ''']
diff --git a/matemat/db/test/test_facade.py b/matemat/db/test/test_facade.py
index d4ab500..16e9b86 100644
--- a/matemat/db/test/test_facade.py
+++ b/matemat/db/test/test_facade.py
@@ -2,9 +2,11 @@
 import unittest
 
 import crypt
+from datetime import datetime, timedelta
 
 from matemat.db import MatematDatabase
-from matemat.db.primitives import User
+from matemat.db.primitives import User, Product, ReceiptPreference, Receipt,\
+    Transaction, Modification, Deposit, Consumption
 from matemat.exceptions import AuthenticationError, DatabaseConsistencyError
 
 
@@ -24,12 +26,13 @@ class DatabaseTest(unittest.TestCase):
                 self.assertEqual('testuser@example.com', row[2])
                 self.assertEqual(0, row[5])
                 self.assertEqual(1, row[6])
+                self.assertEqual(ReceiptPreference.NONE.value, row[7])
                 with self.assertRaises(ValueError):
                     db.create_user('testuser', 'supersecurepassword2', 'testuser2@example.com')
 
     def test_get_user(self) -> None:
         with self.db as db:
-            with db.transaction(exclusive=False):
+            with db.transaction() as c:
                 created = db.create_user('testuser', 'supersecurepassword', 'testuser@example.com',
                                          admin=True, member=False)
                 user = db.get_user(created.id)
@@ -37,8 +40,14 @@ class DatabaseTest(unittest.TestCase):
                 self.assertEqual('testuser@example.com', user.email)
                 self.assertEqual(False, user.is_member)
                 self.assertEqual(True, user.is_admin)
+                self.assertEqual(ReceiptPreference.NONE, user.receipt_pref)
                 with self.assertRaises(ValueError):
                     db.get_user(-1)
+                # Write an invalid receipt preference to the database
+                c.execute('UPDATE users SET receipt_pref = 42 WHERE user_id = ?',
+                          [user.id])
+                with self.assertRaises(DatabaseConsistencyError):
+                    db.get_user(user.id)
 
     def test_list_users(self) -> None:
         with self.db as db:
@@ -49,7 +58,8 @@ class DatabaseTest(unittest.TestCase):
             testuser: User = db.create_user('testuser', 'supersecurepassword', 'testuser@example.com', True, True)
             db.change_touchkey(testuser, '', 'touchkey', verify_password=False)
             db.create_user('anothertestuser', 'otherpassword', 'anothertestuser@example.com', False, True)
-            db.create_user('yatu', 'igotapasswordtoo', 'yatu@example.com', False, False)
+            u = db.create_user('yatu', 'igotapasswordtoo', 'yatu@example.com', False, False)
+            db.change_user(u, agent=None, receipt_pref=ReceiptPreference.WEEKLY)
             users = db.list_users()
             users_with_touchkey = db.list_users(with_touchkey=True)
         self.assertEqual(3, len(users))
@@ -67,6 +77,7 @@ class DatabaseTest(unittest.TestCase):
                 self.assertEqual('yatu@example.com', user.email)
                 self.assertFalse(user.is_member)
                 self.assertFalse(user.is_admin)
+                self.assertEqual(ReceiptPreference.WEEKLY, user.receipt_pref)
             usercheck[user.id] = 1
         self.assertEqual(3, len(usercheck))
         self.assertEqual(1, len(users_with_touchkey))
@@ -91,7 +102,7 @@ class DatabaseTest(unittest.TestCase):
                 except AuthenticationError as e:
                     self.assertEqual('Touchkey not set', e.msg)
                 # Add a touchkey without using the provided function
-                c.execute('''UPDATE users SET touchkey = :tkhash WHERE user_id = :user_id''', {
+                c.execute('''UPDATE users SET touchkey = :tkhash, receipt_pref = 2 WHERE user_id = :user_id''', {
                     'tkhash': crypt.crypt('0123', crypt.mksalt()),
                     'user_id': u.id
                 })
@@ -99,6 +110,7 @@ class DatabaseTest(unittest.TestCase):
             self.assertEqual(u.id, user.id)
             user = db.login('testuser', touchkey='0123')
             self.assertEqual(u.id, user.id)
+            self.assertEqual(ReceiptPreference.MONTHLY, user.receipt_pref)
             with self.assertRaises(AuthenticationError):
                 # Inexistent user should fail
                 db.login('nooone', 'supersecurepassword')
@@ -166,18 +178,24 @@ class DatabaseTest(unittest.TestCase):
         with self.db as db:
             agent = db.create_user('admin', 'supersecurepassword', 'admin@example.com', True, True)
             user = db.create_user('testuser', 'supersecurepassword', 'testuser@example.com', True, True)
-            db.change_user(user, agent, email='newaddress@example.com', is_admin=False, is_member=False, balance=4200)
+            db.change_user(user, agent, email='newaddress@example.com', is_admin=False, is_member=False, balance=4200,
+                           balance_reason='This is a reason!', receipt_pref=ReceiptPreference.MONTHLY)
             # Changes must be reflected in the passed user object
             self.assertEqual('newaddress@example.com', user.email)
             self.assertFalse(user.is_admin)
             self.assertFalse(user.is_member)
             self.assertEqual(4200, user.balance)
+            self.assertEqual(ReceiptPreference.MONTHLY, user.receipt_pref)
             # Changes must be reflected in the database
             checkuser = db.get_user(user.id)
             self.assertEqual('newaddress@example.com', user.email)
             self.assertFalse(checkuser.is_admin)
             self.assertFalse(checkuser.is_member)
             self.assertEqual(4200, checkuser.balance)
+            self.assertEqual(ReceiptPreference.MONTHLY, checkuser.receipt_pref)
+            with db.transaction(exclusive=False) as c:
+                c.execute('SELECT reason FROM modifications LIMIT 1')
+                self.assertEqual('This is a reason!', c.fetchone()[0])
             # Balance change without an agent must fail
             with self.assertRaises(ValueError):
                 db.change_user(user, None, balance=0)
@@ -376,3 +394,186 @@ class DatabaseTest(unittest.TestCase):
                 db.increment_consumption(user1, florapowermate)
             with self.assertRaises(DatabaseConsistencyError):
                 db.increment_consumption(user2, clubmate)
+
+    def test_check_receipt_due(self):
+        with self.db as db:
+            # Receipt preference set to 0
+            user0 = db.create_user('user0', 'supersecurepassword', 'user0@example.com', True, True)
+            # No email, no receipts
+            user1 = db.create_user('user1', 'supersecurepassword', None, True, True)
+            db.change_user(user1, agent=None, receipt_pref=ReceiptPreference.MONTHLY)
+            # Should receive a receipt, has never received a receipt before
+            user2 = db.create_user('user2', 'supersecurepassword', 'user2@example.com', True, True)
+            db.change_user(user2, agent=None, receipt_pref=ReceiptPreference.MONTHLY)
+            # Should receive a receipt, has received receipts before
+            user3 = db.create_user('user3', 'supersecurepassword', 'user3@example.com', True, True)
+            db.change_user(user3, agent=None, receipt_pref=ReceiptPreference.MONTHLY)
+            # Shouldn't receive a receipt, a month hasn't passed since the last receipt
+            user4 = db.create_user('user4', 'supersecurepassword', 'user4@example.com', True, True)
+            db.change_user(user4, agent=None, receipt_pref=ReceiptPreference.MONTHLY)
+            # Should receive a receipt, has been more than a year since the last receipt
+            user5 = db.create_user('user5', 'supersecurepassword', 'user5@example.com', True, True)
+            db.change_user(user5, agent=None, receipt_pref=ReceiptPreference.YEARLY)
+            # Shouldn't receive a receipt, a year hasn't passed since the last receipt
+            user6 = db.create_user('user6', 'supersecurepassword', 'user6@example.com', True, True)
+            db.change_user(user6, agent=None, receipt_pref=ReceiptPreference.YEARLY)
+            # Invalid receipt preference, should raise a ValueError
+            user7 = db.create_user('user7', 'supersecurepassword', 'user7@example.com', True, True)
+            user7.receipt_pref = 42
+
+            twoyears: int = int((datetime.utcnow() - timedelta(days=730)).timestamp())
+            halfyear: int = int((datetime.utcnow() - timedelta(days=183)).timestamp())
+            twomonths: int = int((datetime.utcnow() - timedelta(days=61)).timestamp())
+            halfmonth: int = int((datetime.utcnow() - timedelta(days=15)).timestamp())
+
+            with db.transaction() as c:
+                # Fix creation date for user2
+                c.execute('''
+                UPDATE users SET created = :twomonths WHERE user_id = :user2
+                ''', {
+                    'twomonths': twomonths,
+                    'user2': user2.id
+                })
+                # Create transactions
+                c.execute('''
+                INSERT INTO transactions (ta_id, user_id, value, old_balance, date) VALUES
+                  (1, :user0, 4200, 0, :twomonths),
+                  (2, :user0, 100, 4200, :halfmonth),
+                  (3, :user1, 4200, 0, :twomonths),
+                  (4, :user1, 100, 4200, :halfmonth),
+                  (5, :user2, 4200, 0, :twomonths),
+                  (6, :user2, 100, 4200, :halfmonth),
+                  (7, :user3, 4200, 0, :twomonths),
+                  (8, :user3, 100, 4200, :halfmonth),
+                  (9, :user4, 4200, 0, :twomonths),
+                  (10, :user4, 100, 4200, :halfmonth),
+                  (11, :user5, 4200, 0, :twoyears),
+                  (12, :user5, 100, 4200, :halfyear),
+                  (13, :user6, 4200, 0, :twoyears),
+                  (14, :user6, 100, 4200, :halfyear)
+                ''', {
+                    'twoyears': twoyears,
+                    'halfyear': halfyear,
+                    'twomonths': twomonths,
+                    'halfmonth': halfmonth,
+                    'user0': user0.id,
+                    'user1': user1.id,
+                    'user2': user2.id,
+                    'user3': user3.id,
+                    'user4': user4.id,
+                    'user5': user5.id,
+                    'user6': user6.id
+                })
+                # Create receipts
+                c.execute('''
+                INSERT INTO receipts (user_id, first_ta_id, last_ta_id, date) VALUES
+                  (:user3, 7, 7, :twomonths),
+                  (:user4, 9, 9, :halfmonth),
+                  (:user5, 11, 11, :twoyears),
+                  (:user6, 13, 13, :halfyear)
+                ''', {
+                    'twoyears': twoyears,
+                    'halfyear': halfyear,
+                    'twomonths': twomonths,
+                    'halfmonth': halfmonth,
+                    'user3': user3.id,
+                    'user4': user4.id,
+                    'user5': user5.id,
+                    'user6': user6.id
+                })
+
+            self.assertFalse(db.check_receipt_due(user0))
+            self.assertFalse(self.db.check_receipt_due(user1))
+            self.assertTrue(self.db.check_receipt_due(user2))
+            self.assertTrue(self.db.check_receipt_due(user3))
+            self.assertFalse(self.db.check_receipt_due(user4))
+            self.assertTrue(self.db.check_receipt_due(user5))
+            self.assertFalse(self.db.check_receipt_due(user6))
+            with self.assertRaises(TypeError):
+                self.db.check_receipt_due(user7)
+
+    def test_create_receipt(self):
+        with self.db as db:
+
+            now: datetime = datetime.utcnow()
+            admin: User = db.create_user('admin', 'supersecurepassword', 'admin@example.com', True, True)
+            user: User = db.create_user('user', 'supersecurepassword', 'user@example.com', True, True)
+            product: Product = db.create_product('Flora Power Mate', 200, 200)
+
+            # Create some transactions
+            db.change_user(user, agent=admin,
+                           receipt_pref=ReceiptPreference.MONTHLY,
+                           balance=4200, balance_reason='Here\'s a gift!')
+            db.increment_consumption(user, product)
+            db.deposit(user, 1337)
+            receipt1: Receipt = db.create_receipt(user, write=True)
+
+            with db.transaction() as c:
+                c.execute('SELECT COUNT(receipt_id) FROM receipts')
+                self.assertEqual(1, c.fetchone()[0])
+
+            db.increment_consumption(user, product)
+            db.change_user(user, agent=admin, balance=4200)
+            with db.transaction() as c:
+                # Unknown transactions
+                c.execute('''
+                INSERT INTO transactions (user_id, value, old_balance)
+                SELECT user_id, 500, balance
+                FROM users
+                WHERE user_id = :id
+                ''', [user.id])
+            receipt2: Receipt = db.create_receipt(user, write=False)
+
+            with db.transaction() as c:
+                c.execute('SELECT COUNT(receipt_id) FROM receipts')
+                self.assertEqual(1, c.fetchone()[0])
+
+            self.assertEqual(user, receipt1.user)
+            self.assertEqual(3, len(receipt1.transactions))
+
+            self.assertIsInstance(receipt1.transactions[0], Modification)
+            t10: Modification = receipt1.transactions[0]
+            self.assertEqual(user, receipt1.user)
+            self.assertEqual(4200, t10.value)
+            self.assertEqual(0, t10.old_balance)
+            self.assertEqual(admin.name, t10.agent)
+            self.assertEqual('Here\'s a gift!', t10.reason)
+
+            self.assertIsInstance(receipt1.transactions[1], Consumption)
+            t11: Consumption = receipt1.transactions[1]
+            self.assertEqual(user, receipt1.user)
+            self.assertEqual(-200, t11.value)
+            self.assertEqual(4200, t11.old_balance)
+            self.assertEqual('Flora Power Mate', t11.product)
+
+            self.assertIsInstance(receipt1.transactions[2], Deposit)
+            t12: Deposit = receipt1.transactions[2]
+            self.assertEqual(user, receipt1.user)
+            self.assertEqual(1337, t12.value)
+            self.assertEqual(4000, t12.old_balance)
+
+            self.assertEqual(user, receipt2.user)
+            self.assertEqual(3, len(receipt2.transactions))
+
+            self.assertIsInstance(receipt2.transactions[0], Consumption)
+            t20: Consumption = receipt2.transactions[0]
+            self.assertEqual(user, receipt2.user)
+            self.assertEqual(-200, t20.value)
+            self.assertEqual(5337, t20.old_balance)
+            self.assertEqual('Flora Power Mate', t20.product)
+
+            self.assertIsInstance(receipt2.transactions[1], Modification)
+            t21: Modification = receipt2.transactions[1]
+            self.assertEqual(user, receipt2.user)
+            self.assertEqual(-937, t21.value)
+            self.assertEqual(5137, t21.old_balance)
+            self.assertEqual(admin.name, t21.agent)
+            self.assertEqual(None, t21.reason)
+
+            self.assertIs(type(receipt2.transactions[2]), Transaction)
+            t22: Transaction = receipt2.transactions[2]
+            self.assertEqual(user, receipt2.user)
+            self.assertEqual(500, t22.value)
+            self.assertEqual(4200, t22.old_balance)
+
+# TODO: Test cases for primitive object vs database row mismatch
diff --git a/matemat/db/test/test_migrations.py b/matemat/db/test/test_migrations.py
index 0488a96..707709e 100644
--- a/matemat/db/test/test_migrations.py
+++ b/matemat/db/test/test_migrations.py
@@ -52,7 +52,10 @@ class TestMigrations(unittest.TestCase):
         cursor.execute('PRAGMA user_version = 1')
 
         # Kick off the migration
+        schema_version = self.db.SCHEMA_VERSION
+        self.db.SCHEMA_VERSION = 2
         self.db._setup()
+        self.db.SCHEMA_VERSION = schema_version
 
         # Test whether the new tables were created
         cursor.execute('PRAGMA table_info(transactions)')
@@ -122,3 +125,61 @@ class TestMigrations(unittest.TestCase):
                 ON t.ta_id = c.ta_id
               WHERE t.user_id = 3 AND c.product_id = 2 AND t.value = -150''')
         self.assertEqual(4, cursor.fetchone()[0])
+
+    def test_upgrade_2_to_3(self):
+        # Setup test db with example entries covering - hopefully - all cases
+        self._initialize_db(2)
+        cursor: sqlite3.Cursor = self.db._sqlite_db.cursor()
+        cursor.execute('''
+            INSERT INTO users VALUES
+              (1, 'testadmin', 'a@b.c', '$2a$10$herebehashes', NULL, 1, 1, 1337, 0),
+              (2, 'testuser', NULL, '$2a$10$herebehashes', '$2a$10$herebehashes', 0, 1, 4242, 0),
+              (3, 'alien', NULL, '$2a$10$herebehashes', '$2a$10$herebehashes', 0, 0, 1234, 0),
+              (4, 'neverused', NULL, '$2a$10$herebehashes', '$2a$10$herebehashes', 0, 0, 1234, 1234)
+        ''')
+        cursor.execute('''
+            INSERT INTO products VALUES
+              (1, 'Club Mate', 42, 200, 250),
+              (2, 'Flora Power Mate', 10, 100, 150)
+        ''')
+        cursor.execute('''
+            INSERT INTO transactions VALUES
+              (1, 1, 4200, 0, 1000),  -- deposit
+              (2, 2, 1337, 0, 1001),  -- modification
+              (3, 3, 1337, 0, 1002),  -- modification with deleted agent
+              (4, 2, -200, 1337, 1003),  -- consumption
+              (5, 3, -200, 1337, 1004)  -- consumption with deleted product
+        ''')
+        cursor.execute('''INSERT INTO deposits VALUES (1)''')
+        cursor.execute('''
+            INSERT INTO modifications VALUES
+              (2, 1, 'Account migration'),
+              (3, 42, 'You can''t find out who i am... MUAHAHAHA!!!')''')
+        cursor.execute('''INSERT INTO consumptions VALUES (4, 2), (5, 42)''')
+        cursor.execute('''PRAGMA user_version = 2''')
+
+        # Kick off the migration
+        schema_version = self.db.SCHEMA_VERSION
+        self.db.SCHEMA_VERSION = 3
+        self.db._setup()
+        self.db.SCHEMA_VERSION = schema_version
+
+        # Make sure the receipts table was created
+        cursor.execute('''SELECT COUNT(receipt_id) FROM receipts''')
+        self.assertEqual(0, cursor.fetchone()[0])
+
+        # Make sure users.created was populated with the expected values
+        cursor.execute('''SELECT u.created FROM users AS u ORDER BY u.user_id ASC''')
+        self.assertEqual([(940,), (941,), (942,), (1174,)], cursor.fetchall())
+
+        # Make sure the modifications table was changed to contain the username, or a fallback
+        cursor.execute('''SELECT agent FROM modifications WHERE ta_id = 2''')
+        self.assertEqual('testadmin', cursor.fetchone()[0])
+        cursor.execute('''SELECT agent FROM modifications WHERE ta_id = 3''')
+        self.assertEqual('<unknown>', cursor.fetchone()[0])
+
+        # Make sure the consumptions table was changed to contain the product name, or a fallback
+        cursor.execute('''SELECT product FROM consumptions WHERE ta_id = 4''')
+        self.assertEqual('Flora Power Mate', cursor.fetchone()[0])
+        cursor.execute('''SELECT product FROM consumptions WHERE ta_id = 5''')
+        self.assertEqual('<unknown>', cursor.fetchone()[0])
diff --git a/matemat/db/test/test_wrapper.py b/matemat/db/test/test_wrapper.py
index 0b78890..d661c4f 100644
--- a/matemat/db/test/test_wrapper.py
+++ b/matemat/db/test/test_wrapper.py
@@ -53,12 +53,12 @@ class DatabaseTest(unittest.TestCase):
         with self.db as db:
             with db.transaction() as c:
                 c.execute('''
-                INSERT INTO users VALUES (1, 'testuser', NULL, 'supersecurepassword', NULL, 1, 1, 0, 42)
+                INSERT INTO users VALUES (1, 'testuser', NULL, 'supersecurepassword', NULL, 1, 1, 0, 42, 0, 0)
                 ''')
             c = db._sqlite_db.cursor()
             c.execute("SELECT * FROM users")
             user = c.fetchone()
-            self.assertEqual((1, 'testuser', None, 'supersecurepassword', None, 1, 1, 0, 42), user)
+            self.assertEqual((1, 'testuser', None, 'supersecurepassword', None, 1, 1, 0, 42, 0, 0), user)
 
     def test_transaction_rollback(self) -> None:
         """
@@ -67,9 +67,9 @@ class DatabaseTest(unittest.TestCase):
         with self.db as db:
             try:
                 with db.transaction() as c:
-                    c.execute("""
-                      INSERT INTO users VALUES (1, 'testuser', NULL, 'supersecurepassword', NULL, 1, 1, 0, 42)
-                    """)
+                    c.execute('''
+                      INSERT INTO users VALUES (1, 'testuser', NULL, 'supersecurepassword', NULL, 1, 1, 0, 42, 0, 0)
+                    ''')
                     raise ValueError('This should trigger a rollback')
             except ValueError as e:
                 if str(e) != 'This should trigger a rollback':
diff --git a/matemat/db/wrapper.py b/matemat/db/wrapper.py
index fcf85e7..6441f1c 100644
--- a/matemat/db/wrapper.py
+++ b/matemat/db/wrapper.py
@@ -6,10 +6,10 @@ import sqlite3
 
 from matemat.exceptions import DatabaseConsistencyError
 from matemat.db.schemas import SCHEMAS
-from matemat.db.migrations import migrate_schema_1_to_2
+from matemat.db.migrations import migrate_schema_1_to_2, migrate_schema_2_to_3
 
 
-class Transaction(object):
+class DatabaseTransaction(object):
 
     def __init__(self, db: sqlite3.Connection, exclusive: bool = True) -> None:
         self._db: sqlite3.Connection = db
@@ -43,7 +43,7 @@ class Transaction(object):
 
 class DatabaseWrapper(object):
 
-    SCHEMA_VERSION = 2
+    SCHEMA_VERSION = 3
 
     def __init__(self, filename: str) -> None:
         self._filename: str = filename
@@ -56,13 +56,20 @@ class DatabaseWrapper(object):
     def __exit__(self, exc_type: Any, exc_val: Any, exc_tb: Any) -> None:
         self.close()
 
-    def transaction(self, exclusive: bool = True) -> Transaction:
+    def transaction(self, exclusive: bool = True) -> DatabaseTransaction:
         if self._sqlite_db is None:
             raise RuntimeError(f'Database connection to {self._filename} is not established.')
-        return Transaction(self._sqlite_db, exclusive)
+        return DatabaseTransaction(self._sqlite_db, exclusive)
 
     def _setup(self) -> None:
+        # Enable foreign key enforcement
+        cursor = self._sqlite_db.cursor()
+        cursor.execute('PRAGMA foreign_keys = 1')
+
+        # Create or update schemas if necessary
         with self.transaction() as c:
+            # Defer foreign key enforcement in the setup transaction
+            c.execute('PRAGMA defer_foreign_keys = 1')
             version: int = self._user_version
             if version < 1:
                 # Don't use executescript, as it issues a COMMIT first
@@ -77,8 +84,10 @@ class DatabaseWrapper(object):
     def _upgrade(self, from_version: int, to_version: int) -> None:
         with self.transaction() as c:
             # Note to future s3lph: If there are further migrations, also consider upgrades like 1 -> 3
-            if from_version == 1 and to_version == 2:
+            if from_version == 1 and to_version >= 2:
                 migrate_schema_1_to_2(c)
+            if from_version <= 2 and to_version >= 3:
+                migrate_schema_2_to_3(c)
 
     def connect(self) -> None:
         if self.is_connected():
diff --git a/matemat/util/currency_format.py b/matemat/util/currency_format.py
index a163238..2b7ab31 100644
--- a/matemat/util/currency_format.py
+++ b/matemat/util/currency_format.py
@@ -1,11 +1,12 @@
 
 
-def format_chf(value: int, with_currencysign: bool = True) -> str:
+def format_chf(value: int, with_currencysign: bool = True, plus_sign: bool = False) -> str:
     """
     Formats a centime value into a commonly understood representation ("CHF -13.37").
 
     :param value: The value to format, in centimes.
     :param with_currencysign: Whether to include the currency prefix ("CHF ") in the output.
+    :param plus_sign: Whether to denote positive values with an explicit "+" sign before the value.
     :return: A human-readable string representation.
     """
     sign: str = ''
@@ -13,6 +14,8 @@ def format_chf(value: int, with_currencysign: bool = True) -> str:
         # As // and % round towards -Inf, convert into a positive value and prepend the negative sign
         sign = '-'
         value = -value
+    elif plus_sign:
+        sign = '+'
     # Split into full francs and fractions (centimes)
     full: int = value // 100
     frac: int = value % 100
diff --git a/matemat/util/monthdelta.py b/matemat/util/monthdelta.py
new file mode 100644
index 0000000..49c1fa0
--- /dev/null
+++ b/matemat/util/monthdelta.py
@@ -0,0 +1,29 @@
+
+from typing import Tuple
+
+from datetime import datetime, timedelta
+import calendar
+
+
+def add_months(d: datetime, months: int) -> datetime:
+    """
+    Add the given number of months to the passed date, considering the varying numbers of days in a month.
+    :param d: The date time to add to.
+    :param months: The number of months to add to.
+    :return: A datetime object offset by the requested number of months.
+    """
+    if not isinstance(d, datetime) or not isinstance(months, int):
+        raise TypeError()
+    if months < 0:
+        raise ValueError('Can only add a positive number of months.')
+    nextmonth: Tuple[int, int] = (d.year, d.month)
+    days: int = 0
+    # Iterate the months between the passed date and the target month
+    for i in range(months):
+        days += calendar.monthlen(*nextmonth)
+        nextmonth = calendar.nextmonth(*nextmonth)
+    # Set the day of month temporarily to 1, then add the day offset to reach the 1st of the target month
+    newdate: datetime = d.replace(day=1) + timedelta(days=days)
+    # Re-set the day of month to the intended value, but capped by the max. day in the target month
+    newdate = newdate.replace(day=min(d.day, calendar.monthlen(newdate.year, newdate.month)))
+    return newdate
diff --git a/matemat/util/test/test_currency_format.py b/matemat/util/test/test_currency_format.py
index b2f6eb5..f8d6241 100644
--- a/matemat/util/test/test_currency_format.py
+++ b/matemat/util/test/test_currency_format.py
@@ -9,38 +9,56 @@ class TestCurrencyFormat(unittest.TestCase):
     def test_format_zero(self):
         self.assertEqual('CHF 0.00', format_chf(0))
         self.assertEqual('0.00', format_chf(0, False))
+        self.assertEqual('CHF +0.00', format_chf(0, plus_sign=True))
+        self.assertEqual('+0.00', format_chf(0, False, plus_sign=True))
 
     def test_format_positive_full(self):
         self.assertEqual('CHF 42.00', format_chf(4200))
         self.assertEqual('42.00', format_chf(4200, False))
+        self.assertEqual('CHF +42.00', format_chf(4200, plus_sign=True))
+        self.assertEqual('+42.00', format_chf(4200, False, plus_sign=True))
 
     def test_format_negative_full(self):
         self.assertEqual('CHF -42.00', format_chf(-4200))
         self.assertEqual('-42.00', format_chf(-4200, False))
+        self.assertEqual('CHF -42.00', format_chf(-4200, plus_sign=True))
+        self.assertEqual('-42.00', format_chf(-4200, False, plus_sign=True))
 
     def test_format_positive_frac(self):
         self.assertEqual('CHF 13.37', format_chf(1337))
         self.assertEqual('13.37', format_chf(1337, False))
+        self.assertEqual('CHF +13.37', format_chf(1337, plus_sign=True))
+        self.assertEqual('+13.37', format_chf(1337, False, plus_sign=True))
 
     def test_format_negative_frac(self):
         self.assertEqual('CHF -13.37', format_chf(-1337))
         self.assertEqual('-13.37', format_chf(-1337, False))
+        self.assertEqual('CHF -13.37', format_chf(-1337, plus_sign=True))
+        self.assertEqual('-13.37', format_chf(-1337, False, plus_sign=True))
 
     def test_format_pad_left_positive(self):
         self.assertEqual('CHF 0.01', format_chf(1))
         self.assertEqual('0.01', format_chf(1, False))
+        self.assertEqual('CHF +0.01', format_chf(1, plus_sign=True))
+        self.assertEqual('+0.01', format_chf(1, False, plus_sign=True))
 
     def test_format_pad_left_negative(self):
         self.assertEqual('CHF -0.01', format_chf(-1))
         self.assertEqual('-0.01', format_chf(-1, False))
+        self.assertEqual('CHF -0.01', format_chf(-1, plus_sign=True))
+        self.assertEqual('-0.01', format_chf(-1, False, plus_sign=True))
 
     def test_format_pad_right_positive(self):
         self.assertEqual('CHF 4.20', format_chf(420))
         self.assertEqual('4.20', format_chf(420, False))
+        self.assertEqual('CHF +4.20', format_chf(420, plus_sign=True))
+        self.assertEqual('+4.20', format_chf(420, False, plus_sign=True))
 
     def test_format_pad_right_negative(self):
         self.assertEqual('CHF -4.20', format_chf(-420))
         self.assertEqual('-4.20', format_chf(-420, False))
+        self.assertEqual('CHF -4.20', format_chf(-420, plus_sign=True))
+        self.assertEqual('-4.20', format_chf(-420, False, plus_sign=True))
 
     def test_parse_empty(self):
         with self.assertRaises(ValueError):
@@ -52,20 +70,29 @@ class TestCurrencyFormat(unittest.TestCase):
 
     def test_parse_zero(self):
         self.assertEqual(0, parse_chf('CHF0'))
+        self.assertEqual(0, parse_chf('CHF-0'))
+        self.assertEqual(0, parse_chf('CHF+0'))
         self.assertEqual(0, parse_chf('CHF 0'))
+        self.assertEqual(0, parse_chf('CHF +0'))
         self.assertEqual(0, parse_chf('CHF -0'))
         self.assertEqual(0, parse_chf('CHF 0.'))
         self.assertEqual(0, parse_chf('CHF 0.0'))
         self.assertEqual(0, parse_chf('CHF 0.00'))
+        self.assertEqual(0, parse_chf('CHF +0.'))
+        self.assertEqual(0, parse_chf('CHF +0.0'))
+        self.assertEqual(0, parse_chf('CHF +0.00'))
         self.assertEqual(0, parse_chf('CHF -0.'))
         self.assertEqual(0, parse_chf('CHF -0.0'))
         self.assertEqual(0, parse_chf('CHF -0.00'))
         self.assertEqual(0, parse_chf('0'))
-        self.assertEqual(0, parse_chf('0'))
+        self.assertEqual(0, parse_chf('+0'))
         self.assertEqual(0, parse_chf('-0'))
         self.assertEqual(0, parse_chf('0.'))
         self.assertEqual(0, parse_chf('0.0'))
         self.assertEqual(0, parse_chf('0.00'))
+        self.assertEqual(0, parse_chf('+0.'))
+        self.assertEqual(0, parse_chf('+0.0'))
+        self.assertEqual(0, parse_chf('+0.00'))
         self.assertEqual(0, parse_chf('-0.'))
         self.assertEqual(0, parse_chf('-0.0'))
         self.assertEqual(0, parse_chf('-0.00'))
@@ -80,6 +107,16 @@ class TestCurrencyFormat(unittest.TestCase):
         self.assertEqual(4200, parse_chf('CHF 42.0'))
         self.assertEqual(4200, parse_chf('42.0'))
 
+    def test_parse_positive_full_with_sign(self):
+        self.assertEqual(4200, parse_chf('CHF +42.00'))
+        self.assertEqual(4200, parse_chf('+42.00'))
+        self.assertEqual(4200, parse_chf('CHF +42'))
+        self.assertEqual(4200, parse_chf('+42'))
+        self.assertEqual(4200, parse_chf('CHF +42.'))
+        self.assertEqual(4200, parse_chf('+42.'))
+        self.assertEqual(4200, parse_chf('CHF +42.0'))
+        self.assertEqual(4200, parse_chf('+42.0'))
+
     def test_parse_negative_full(self):
         self.assertEqual(-4200, parse_chf('CHF -42.00'))
         self.assertEqual(-4200, parse_chf('-42.00'))
@@ -94,6 +131,10 @@ class TestCurrencyFormat(unittest.TestCase):
         self.assertEqual(1337, parse_chf('CHF 13.37'))
         self.assertEqual(1337, parse_chf('13.37'))
 
+    def test_parse_positive_frac_with_sign(self):
+        self.assertEqual(1337, parse_chf('CHF +13.37'))
+        self.assertEqual(1337, parse_chf('+13.37'))
+
     def test_parse_negative_frac(self):
         self.assertEqual(-1337, parse_chf('CHF -13.37'))
         self.assertEqual(-1337, parse_chf('-13.37'))
@@ -102,6 +143,10 @@ class TestCurrencyFormat(unittest.TestCase):
         self.assertEqual(1, parse_chf('CHF 0.01'))
         self.assertEqual(1, parse_chf('0.01'))
 
+    def test_parse_pad_left_positive_with_sign(self):
+        self.assertEqual(1, parse_chf('CHF +0.01'))
+        self.assertEqual(1, parse_chf('+0.01'))
+
     def test_parse_pad_left_negative(self):
         self.assertEqual(-1, parse_chf('CHF -0.01'))
         self.assertEqual(-1, parse_chf('-0.01'))
@@ -112,6 +157,12 @@ class TestCurrencyFormat(unittest.TestCase):
         self.assertEqual(420, parse_chf('CHF 4.2'))
         self.assertEqual(420, parse_chf('4.2'))
 
+    def test_parse_pad_right_positive_with_sign(self):
+        self.assertEqual(420, parse_chf('CHF +4.20'))
+        self.assertEqual(420, parse_chf('+4.20'))
+        self.assertEqual(420, parse_chf('CHF +4.2'))
+        self.assertEqual(420, parse_chf('+4.2'))
+
     def test_parse_pad_right_negative(self):
         self.assertEqual(-420, parse_chf('CHF -4.20'))
         self.assertEqual(-420, parse_chf('-4.20'))
@@ -121,10 +172,14 @@ class TestCurrencyFormat(unittest.TestCase):
     def test_parse_too_many_decimals(self):
         with self.assertRaises(ValueError):
             parse_chf('123.456')
+        with self.assertRaises(ValueError):
+            parse_chf('-123.456')
         with self.assertRaises(ValueError):
             parse_chf('CHF 0.456')
         with self.assertRaises(ValueError):
             parse_chf('CHF 0.450')
+        with self.assertRaises(ValueError):
+            parse_chf('CHF +0.456')
 
     def test_parse_wrong_separator(self):
         with self.assertRaises(ValueError):
@@ -137,3 +192,7 @@ class TestCurrencyFormat(unittest.TestCase):
             parse_chf('13.-7')
         with self.assertRaises(ValueError):
             parse_chf('CHF 13.-7')
+        with self.assertRaises(ValueError):
+            parse_chf('+13.-7')
+        with self.assertRaises(ValueError):
+            parse_chf('CHF -13.-7')
diff --git a/matemat/util/test/test_monthdelta.py b/matemat/util/test/test_monthdelta.py
new file mode 100644
index 0000000..98def9a
--- /dev/null
+++ b/matemat/util/test/test_monthdelta.py
@@ -0,0 +1,61 @@
+
+import unittest
+
+from datetime import datetime
+
+from matemat.util.monthdelta import add_months
+
+
+class TestMonthDelta(unittest.TestCase):
+
+    def test_monthdelta_zero(self):
+        date = datetime(2018, 9, 8, 13, 37, 42)
+        offset_date = date
+        self.assertEqual(offset_date, add_months(date, 0))
+
+    def test_monthdelta_one(self):
+        date = datetime(2018, 9, 8, 13, 37, 42)
+        offset_date = date.replace(month=10)
+        self.assertEqual(offset_date, add_months(date, 1))
+
+    def test_monthdelta_two(self):
+        date = datetime(2018, 9, 8, 13, 37, 42)
+        offset_date = date.replace(month=11)
+        self.assertEqual(offset_date, add_months(date, 2))
+
+    def test_monthdelta_yearwrap(self):
+        date = datetime(2018, 9, 8, 13, 37, 42)
+        offset_date = date.replace(year=2019, month=1)
+        self.assertEqual(offset_date, add_months(date, 4))
+
+    def test_monthdelta_yearwrap_five(self):
+        date = datetime(2018, 9, 8, 13, 37, 42)
+        offset_date = date.replace(year=2023, month=3)
+        self.assertEqual(offset_date, add_months(date, 54))
+
+    def test_monthdelta_rounddown_31_30(self):
+        date = datetime(2018, 3, 31, 13, 37, 42)
+        offset_date = date.replace(month=4, day=30)
+        self.assertEqual(offset_date, add_months(date, 1))
+
+    def test_monthdelta_rounddown_feb(self):
+        date = datetime(2018, 1, 31, 13, 37, 42)
+        offset_date = date.replace(month=2, day=28)
+        self.assertEqual(offset_date, add_months(date, 1))
+
+    def test_monthdelta_rounddown_feb_leap(self):
+        date = datetime(2020, 1, 31, 13, 37, 42)
+        offset_date = date.replace(month=2, day=29)
+        self.assertEqual(offset_date, add_months(date, 1))
+
+    def test_fail_negative(self):
+        date = datetime(2020, 1, 31, 13, 37, 42)
+        with self.assertRaises(ValueError):
+            add_months(date, -1)
+
+    def test_fail_type(self):
+        date = datetime(2020, 1, 31, 13, 37, 42)
+        with self.assertRaises(TypeError):
+            add_months(date, 1.2)
+        with self.assertRaises(TypeError):
+            add_months(42, 1)
diff --git a/matemat/webserver/__init__.py b/matemat/webserver/__init__.py
index bd62400..4519023 100644
--- a/matemat/webserver/__init__.py
+++ b/matemat/webserver/__init__.py
@@ -8,5 +8,5 @@ server will attempt to serve the request with a static resource in a previously
 
 from .requestargs import RequestArgument, RequestArguments
 from .responses import PageletResponse, RedirectResponse, TemplateResponse
-from .httpd import MatematWebserver, HttpHandler, pagelet, pagelet_init
+from .httpd import MatematWebserver, HttpHandler, pagelet, pagelet_init, pagelet_cron
 from .config import parse_config_file
diff --git a/matemat/webserver/httpd.py b/matemat/webserver/httpd.py
index f38005c..8d72d61 100644
--- a/matemat/webserver/httpd.py
+++ b/matemat/webserver/httpd.py
@@ -11,6 +11,7 @@ from http.server import HTTPServer, BaseHTTPRequestHandler
 from http.cookies import SimpleCookie
 from uuid import uuid4
 from datetime import datetime, timedelta
+from threading import Event, Timer, Thread
 
 import jinja2
 
@@ -41,6 +42,9 @@ _PAGELET_PATHS: Dict[str, Callable[[str,  # HTTP method (GET, POST, ...)
 # The pagelet initialization functions, to be executed upon startup
 _PAGELET_INIT_FUNCTIONS: Set[Callable[[Dict[str, str], logging.Logger], None]] = set()
 
+_PAGELET_CRON_STATIC_EVENT: Event = Event()
+_PAGELET_CRON_RUNNER: Callable[[Callable[[Dict[str, str], jinja2.Environment, logging.Logger], None]], None] = None
+
 # Inactivity timeout for client sessions
 _SESSION_TIMEOUT: int = 3600
 _MAX_POST: int = 1_000_000
@@ -118,6 +122,90 @@ def pagelet_init(fun: Callable[[Dict[str, str], logging.Logger], None]):
     _PAGELET_INIT_FUNCTIONS.add(fun)
 
 
+class _GlobalEventTimer(Thread):
+    """
+    A timer similar to threading.Timer, except that waits on an externally supplied threading.Event instance,
+    therefore allowing all timers waiting on the same event to be cancelled at once.
+    """
+
+    def __init__(self, interval: float, event: Event, fun, *args, **kwargs):
+        """
+        Create a new _GlobalEventTimer.
+        :param interval: The delay after which to run the function.
+        :param event: The external threading.Event to wait on.
+        :param fun: The function to call.
+        :param args: The positional arguments to pass to the function.
+        :param kwargs: The keyword arguments to pass to the function.
+        """
+        Thread.__init__(self)
+        self.interval = interval
+        self.fun = fun
+        self.args = args if args is not None else []
+        self.kwargs = kwargs if kwargs is not None else {}
+        self.event = event
+
+    def run(self):
+        self.event.wait(self.interval)
+        if not self.event.is_set():
+            self.fun(*self.args, **self.kwargs)
+        # Do NOT call event.set(), as done in threading.Timer, as that would cancel all other timers
+
+
+def pagelet_cron(weeks: int = 0,
+                 days: int = 0,
+                 hours: int = 0,
+                 seconds: int = 0,
+                 minutes: int = 0,
+                 milliseconds: int = 0,
+                 microseconds: int = 0):
+    """
+    Annotate a function to act as a pagelet cron function.  The function will be called in a regular interval, defined
+    by the arguments passed to the decorator, which are passed to a timedelta object.
+
+    The function must have the following signature:
+
+        (config: Dict[str, str], jinja_env: jinja2.Environment, logger: logging.Logger) -> None
+
+        config:       The mutable dictionary of variables read from the [Pagelets] section of the configuration file.
+        jinja_env:    The Jinja2 environment used by the web server.
+        logger:       The server's logger instance.
+        returns:      Nothing.
+
+    :param weeks: Number of weeks in the interval.
+    :param days: Number of days in the interval.
+    :param hours: Number of hours in the interval.
+    :param seconds: Number of seconds in the interval.
+    :param minutes: Number of minutes in the interval.
+    :param milliseconds: Number of milliseconds in the interval.
+    :param microseconds: Number of microseconds in the interval.
+    """
+
+    def cron_wrapper(fun: Callable[[Dict[str, str], jinja2.Environment, logging.Logger], None]):
+        # Create the timedelta object
+        delta: timedelta = timedelta(weeks=weeks,
+                                     days=days,
+                                     hours=hours,
+                                     seconds=seconds,
+                                     minutes=minutes,
+                                     milliseconds=milliseconds,
+                                     microseconds=microseconds)
+
+        # This function is called once in the specified interval
+        def cron():
+            # Set a new timer
+            t: Timer = _GlobalEventTimer(delta.total_seconds(), _PAGELET_CRON_STATIC_EVENT, cron)
+            t.start()
+            # Have the cron job be picked up by the cron runner provided by the web server
+            if _PAGELET_CRON_RUNNER is not None:
+                _PAGELET_CRON_RUNNER(fun)
+
+        # Set a timer to run the cron job after the specified interval
+        timer: Timer = _GlobalEventTimer(delta.total_seconds(), _PAGELET_CRON_STATIC_EVENT, cron)
+        timer.start()
+
+    return cron_wrapper
+
+
 class MatematHTTPServer(HTTPServer):
     """
     A http.server.HTTPServer subclass that acts as a container for data that must be persistent between requests.
@@ -212,17 +300,34 @@ class MatematWebserver(object):
         running.  If any exception is raised in the initialization phase, the program is terminated with a non-zero
         exit code.
         """
+        global _PAGELET_CRON_RUNNER
         try:
-            # Run all pagelet initialization functions
-            for fun in _PAGELET_INIT_FUNCTIONS:
-                fun(self._httpd.pagelet_variables, self._httpd.logger)
+            try:
+                # Run all pagelet initialization functions
+                for fun in _PAGELET_INIT_FUNCTIONS:
+                    fun(self._httpd.pagelet_variables, self._httpd.logger)
+                # Set pagelet cron runner to self
+                _PAGELET_CRON_RUNNER = self._cron_runner
+            except BaseException as e:
+                # If an error occurs, log it and terminate
+                self._httpd.logger.exception(e)
+                self._httpd.logger.critical('An initialization pagelet raised an error.  Stopping.')
+                raise e
+            # If pagelet initialization went fine, start the HTTP server
+            self._httpd.serve_forever()
+        finally:
+            # Cancel all cron timers at once when the webserver is shutting down
+            _PAGELET_CRON_STATIC_EVENT.set()
+
+    def _cron_runner(self, fun: Callable[[Dict[str, str], jinja2.Environment, logging.Logger], None]):
+        self._httpd.logger.info('Executing cron job "%s"', fun.__name__)
+        try:
+            fun(self._httpd.pagelet_variables,
+                self._httpd.jinja_env,
+                self._httpd.logger)
+            self._httpd.logger.info('Completed cron job "%s"', fun.__name__)
         except BaseException as e:
-            # If an error occurs, log it and terminate
-            self._httpd.logger.exception(e)
-            self._httpd.logger.critical('An initialization pagelet raised an error.  Stopping.')
-            raise e
-        # If pagelet initialization went fine, start the HTTP server
-        self._httpd.serve_forever()
+            self._httpd.logger.exception('Cron job "%s" failed:', fun.__name__, exc_info=e)
 
 
 class HttpHandler(BaseHTTPRequestHandler):
diff --git a/matemat/webserver/pagelets/__init__.py b/matemat/webserver/pagelets/__init__.py
index 43b7f31..3cdcad8 100644
--- a/matemat/webserver/pagelets/__init__.py
+++ b/matemat/webserver/pagelets/__init__.py
@@ -15,3 +15,4 @@ from .admin import admin
 from .moduser import moduser
 from .modproduct import modproduct
 from .userbootstrap import userbootstrap
+from .receipt_smtp_cron import receipt_smtp_cron
diff --git a/matemat/webserver/pagelets/admin.py b/matemat/webserver/pagelets/admin.py
index b84db3c..d1866b2 100644
--- a/matemat/webserver/pagelets/admin.py
+++ b/matemat/webserver/pagelets/admin.py
@@ -5,7 +5,7 @@ import magic
 
 from matemat.webserver import pagelet, RequestArguments, PageletResponse, RedirectResponse, TemplateResponse
 from matemat.db import MatematDatabase
-from matemat.db.primitives import User
+from matemat.db.primitives import User, ReceiptPreference
 from matemat.exceptions import DatabaseConsistencyError, HttpException
 
 
@@ -47,7 +47,8 @@ def admin(method: str,
         # Render the "Admin/Settings" page
         return TemplateResponse('admin.html',
                                 authuser=user, authlevel=authlevel, users=users, products=products,
-                                setupname=config['InstanceName'])
+                                receipt_preference_class=ReceiptPreference,
+                                setupname=config['InstanceName'], config_smtp_enabled=config['SmtpSendReceipts'])
 
 
 def handle_change(args: RequestArguments, user: User, db: MatematDatabase, config: Dict[str, str]) -> None:
@@ -73,9 +74,13 @@ def handle_change(args: RequestArguments, user: User, db: MatematDatabase, confi
             # An empty e-mail field should be interpreted as NULL
             if len(email) == 0:
                 email = None
-            # Attempt to update username and e-mail
             try:
-                db.change_user(user, agent=None, name=username, email=email)
+                receipt_pref = ReceiptPreference(int(str(args.receipt_pref)))
+            except ValueError:
+                return
+            # Attempt to update username, e-mail and receipt preference
+            try:
+                db.change_user(user, agent=None, name=username, email=email, receipt_pref=receipt_pref)
             except DatabaseConsistencyError:
                 return
 
diff --git a/matemat/webserver/pagelets/initialization.py b/matemat/webserver/pagelets/initialization.py
index 27636b6..fcb94d9 100644
--- a/matemat/webserver/pagelets/initialization.py
+++ b/matemat/webserver/pagelets/initialization.py
@@ -23,6 +23,31 @@ def initialization(config: Dict[str, str],
     if 'DatabaseFile' not in config:
         config['DatabaseFile'] = './matemat.db'
         logger.warning('Property \'DatabaseFile\' not set, using \'./matemat.db\'')
+    if 'SmtpSendReceipts' not in config:
+        config['SmtpSendReceipts'] = '0'
+        logger.warning('Property \'SmtpSendReceipts\' not set, using \'0\'')
+    if config['SmtpSendReceipts'] == '1':
+        if 'SmtpFrom' not in config:
+            logger.fatal('\'SmtpSendReceipts\' set to \'1\', but \'SmtpFrom\' missing.')
+            raise KeyError()
+        if 'SmtpSubj' not in config:
+            logger.fatal('\'SmtpSendReceipts\' set to \'1\', but \'SmtpSubj\' missing.')
+            raise KeyError()
+        if 'SmtpHost' not in config:
+            logger.fatal('\'SmtpSendReceipts\' set to \'1\', but \'SmtpHost\' missing.')
+            raise KeyError()
+        if 'SmtpPort' not in config:
+            logger.fatal('\'SmtpSendReceipts\' set to \'1\', but \'SmtpPort\' missing.')
+            raise KeyError()
+        if 'SmtpUser' not in config:
+            logger.fatal('\'SmtpSendReceipts\' set to \'1\', but \'SmtpUser\' missing.')
+            raise KeyError()
+        if 'SmtpPass' not in config:
+            logger.fatal('\'SmtpSendReceipts\' set to \'1\', but \'SmtpPass\' missing.')
+            raise KeyError()
+        if 'SmtpEnforceTLS' not in config:
+            config['SmtpEnforceTLS'] = '1'
+            logger.warning('Property \'SmtpEnforceTLS\' not set, using \'1\'')
     with MatematDatabase(config['DatabaseFile']):
         # Connect to the database to create it and perform any schema migrations
         pass
diff --git a/matemat/webserver/pagelets/moduser.py b/matemat/webserver/pagelets/moduser.py
index 0b535f1..8be086c 100644
--- a/matemat/webserver/pagelets/moduser.py
+++ b/matemat/webserver/pagelets/moduser.py
@@ -1,11 +1,11 @@
-from typing import Any, Dict, Union
+from typing import Any, Dict, Optional, Union
 
 import os
 import magic
 
 from matemat.webserver import pagelet, RequestArguments, PageletResponse, RedirectResponse, TemplateResponse
 from matemat.db import MatematDatabase
-from matemat.db.primitives import User
+from matemat.db.primitives import User, ReceiptPreference
 from matemat.exceptions import DatabaseConsistencyError, HttpException
 from matemat.util.currency_format import parse_chf
 
@@ -56,7 +56,8 @@ def moduser(method: str,
         # Render the "Modify User" page
         return TemplateResponse('moduser.html',
                                 authuser=authuser, user=user, authlevel=authlevel,
-                                setupname=config['InstanceName'])
+                                receipt_preference_class=ReceiptPreference,
+                                setupname=config['InstanceName'], config_smtp_enabled=config['SmtpSendReceipts'])
 
 
 def handle_change(args: RequestArguments, user: User, authuser: User, db: MatematDatabase, config: Dict[str, str]) \
@@ -87,13 +88,24 @@ def handle_change(args: RequestArguments, user: User, authuser: User, db: Matema
     # Admin requested update of the user's details
     elif change == 'update':
         # Only write a change if all properties of the user are present in the request arguments
-        if 'username' not in args or 'email' not in args or 'password' not in args or 'balance' not in args:
+        if 'username' not in args or \
+                'email' not in args or \
+                'password' not in args or \
+                'balance' not in args or \
+                'receipt_pref' not in args:
             return
         # Read the properties from the request arguments
         username = str(args.username)
         email = str(args.email)
+        try:
+            receipt_pref = ReceiptPreference(int(str(args.receipt_pref)))
+        except ValueError:
+            return
         password = str(args.password)
         balance = parse_chf(str(args.balance))
+        balance_reason: Optional[str] = str(args.reason)
+        if balance_reason == '':
+            balance_reason = None
         is_member = 'ismember' in args
         is_admin = 'isadmin' in args
         # An empty e-mail field should be interpreted as NULL
@@ -106,7 +118,7 @@ def handle_change(args: RequestArguments, user: User, authuser: User, db: Matema
                 db.change_password(user, '', password, verify_password=False)
             # Write the user detail changes
             db.change_user(user, agent=authuser, name=username, email=email, is_member=is_member, is_admin=is_admin,
-                           balance=balance)
+                           balance=balance, balance_reason=balance_reason, receipt_pref=receipt_pref)
         except DatabaseConsistencyError:
             return
         # If a new avatar was uploaded, process it
diff --git a/matemat/webserver/pagelets/receipt_smtp_cron.py b/matemat/webserver/pagelets/receipt_smtp_cron.py
new file mode 100644
index 0000000..389cab1
--- /dev/null
+++ b/matemat/webserver/pagelets/receipt_smtp_cron.py
@@ -0,0 +1,98 @@
+from typing import Dict, List, Tuple
+
+import logging
+
+import smtplib as smtp
+from email.mime.multipart import MIMEMultipart
+from email.mime.text import MIMEText
+from jinja2 import Environment, Template
+
+from matemat.webserver import pagelet_cron
+from matemat.db import MatematDatabase
+from matemat.db.primitives import User, Receipt
+from matemat.util.currency_format import format_chf
+
+
+@pagelet_cron(hours=6)
+def receipt_smtp_cron(config: Dict[str, str],
+                      jinja_env: Environment,
+                      logger: logging.Logger) -> None:
+    if config['SmtpSendReceipts'] != '1':
+        # Sending receipts via mail is disabled
+        return
+    logger.info('Searching users due for receipts.')
+    receipts: List[Receipt] = []
+    # Connect to the database
+    with MatematDatabase(config['DatabaseFile']) as db:
+        users: List[User] = db.list_users()
+        for user in users:
+            if user.email is None:
+                logger.debug('User "%s" has no e-mail address.', user.name)
+            if db.check_receipt_due(user):
+                logger.info('Generating receipt for user "%s".', user.name)
+                # Generate receipts that are due
+                receipt: Receipt = db.create_receipt(user, write=True)
+                receipts.append(receipt)
+            else:
+                logger.debug('No receipt due for user "%s".', user.name)
+    # Send all generated receipts via e-mailgi
+    if len(receipts) > 0:
+        _send_receipt_mails(receipts, jinja_env, logger, config)
+
+
+def _send_receipt_mails(receipts: List[Receipt],
+                        jinja_env: Environment,
+                        logger: logging.Logger,
+                        config: Dict[str, str]) -> None:
+    mails: List[Tuple[str, MIMEMultipart]] = []
+    for receipt in receipts:
+        if receipt.user.email is None:
+            continue
+        # Create a new message object
+        msg: MIMEMultipart = MIMEMultipart()
+        msg['From'] = config['SmtpFrom']
+        msg['To'] = receipt.user.email
+        msg['Subject'] = config['SmtpSubj']
+        # Format the receipt properties for the text representation
+        fdate: str = receipt.from_date.strftime('%d.%m.%Y, %H:%M')
+        tdate: str = receipt.to_date.strftime('%d.%m.%Y, %H:%M')
+        username: str = receipt.user.name.rjust(40)
+        if len(receipt.transactions) == 0:
+            fbal: str = format_chf(receipt.user.balance).rjust(12)
+        else:
+            fbal = format_chf(receipt.transactions[0].old_balance).rjust(12)
+        tbal: str = format_chf(receipt.user.balance).rjust(12)
+        # Render the receipt
+        template: Template = jinja_env.get_template('receipt.txt')
+        rendered: str = template.render(fdate=fdate, tdate=tdate, user=username, fbal=fbal, tbal=tbal,
+                                        receipt_id=receipt.id, transactions=receipt.transactions,
+                                        instance_name=config['InstanceName'])
+        # Put the rendered receipt in the message body
+        body: MIMEText = MIMEText(rendered)
+        msg.attach(body)
+        mails.append((receipt.user.email, msg))
+
+    # Connect to the SMTP Server
+    con: smtp.SMTP = smtp.SMTP(config['SmtpHost'], config['SmtpPort'])
+    try:
+        # Attempt to upgrade to a TLS connection
+        try:
+            con.starttls()
+        except BaseException:
+            # If STARTTLS failed, only continue if explicitly requested by configuration
+            if config['SmtpEnforceTLS'] != '0':
+                logger.error('STARTTLS not supported by SMTP server, aborting!')
+                return
+            else:
+                logger.warning('Sending e-mails in plain text as requested by SmtpEnforceTLS=0.')
+        # Send SMTP login credentials
+        con.login(config['SmtpUser'], config['SmtpPass'])
+
+        # Send the e-mails
+        for to, msg in mails:
+            logger.info('Sending mail to %s', to)
+            con.sendmail(config['SmtpFrom'], to, msg.as_string())
+    except smtp.SMTPException as e:
+        logger.exception('Exception while sending receipt e-mails', exc_info=e)
+    finally:
+        con.close()
diff --git a/matemat/webserver/test/test_config.py b/matemat/webserver/test/test_config.py
index e2ad985..4fee839 100644
--- a/matemat/webserver/test/test_config.py
+++ b/matemat/webserver/test/test_config.py
@@ -30,6 +30,15 @@ Name=Matemat
 UploadDir= /var/test/static/upload
 DatabaseFile=/var/test/db/test.db
 
+SmtpSendReceipts=1
+SmtpEnforceTLS=0
+SmtpFrom=matemat@example.com
+SmtpSubj=Matemat Receipt
+SmtpHost=smtp.example.com
+SmtpPort=587
+SmtpUser=matemat@example.com
+SmtpPass=SuperSecurePassword
+
 [HttpHeaders]
 Content-Security-Policy = default-src: 'self';
 X-I-Am-A-Header = andthisismyvalue
@@ -42,6 +51,8 @@ Port=443
 [Pagelets]
 Name=Matemat (Unit Test 2)
 
+SmtpSendReceipts=1
+
 [HttpHeaders]
 X-I-Am-A-Header = andthisismyothervalue
 '''
@@ -153,6 +164,14 @@ class TestConfig(TestCase):
         self.assertEqual('Matemat\n(Unit Test)', config['pagelet_variables']['Name'])
         self.assertEqual('/var/test/static/upload', config['pagelet_variables']['UploadDir'])
         self.assertEqual('/var/test/db/test.db', config['pagelet_variables']['DatabaseFile'])
+        self.assertEqual('1', config['pagelet_variables']['SmtpSendReceipts'])
+        self.assertEqual('0', config['pagelet_variables']['SmtpEnforceTLS'])
+        self.assertEqual('matemat@example.com', config['pagelet_variables']['SmtpFrom'])
+        self.assertEqual('Matemat Receipt', config['pagelet_variables']['SmtpSubj'])
+        self.assertEqual('smtp.example.com', config['pagelet_variables']['SmtpHost'])
+        self.assertEqual('587', config['pagelet_variables']['SmtpPort'])
+        self.assertEqual('matemat@example.com', config['pagelet_variables']['SmtpUser'])
+        self.assertEqual('SuperSecurePassword', config['pagelet_variables']['SmtpPass'])
         self.assertIsInstance(config['headers'], dict)
         self.assertEqual(2, len(config['headers']))
         self.assertEqual('default-src: \'self\';', config['headers']['Content-Security-Policy'])
diff --git a/matemat/webserver/test/test_pagelet_cron.py b/matemat/webserver/test/test_pagelet_cron.py
new file mode 100644
index 0000000..4db29f8
--- /dev/null
+++ b/matemat/webserver/test/test_pagelet_cron.py
@@ -0,0 +1,65 @@
+from typing import Dict
+
+import unittest
+
+import logging
+from threading import Lock, Thread, Timer
+from time import sleep
+import jinja2
+
+from matemat.webserver import MatematWebserver, pagelet_cron
+
+lock: Lock = Lock()
+
+cron1called: int = 0
+cron2called: int = 0
+
+
+@pagelet_cron(seconds=4)
+def cron1(config: Dict[str, str],
+          jinja_env: jinja2.Environment,
+          logger: logging.Logger) -> None:
+    global cron1called
+    with lock:
+        cron1called += 1
+
+
+@pagelet_cron(seconds=3)
+def cron2(config: Dict[str, str],
+          jinja_env: jinja2.Environment,
+          logger: logging.Logger) -> None:
+    global cron2called
+    with lock:
+        cron2called += 1
+
+
+class TestPageletCron(unittest.TestCase):
+
+    def setUp(self):
+        self.srv = MatematWebserver('::1', 0, '/nonexistent', '/nonexistent', {}, {},
+                                    logging.NOTSET, logging.NullHandler())
+        self.srv_port = int(self.srv._httpd.socket.getsockname()[1])
+        self.timer = Timer(10.0, self.srv._httpd.shutdown)
+        self.timer.start()
+
+    def tearDown(self):
+        self.timer.cancel()
+        if self.srv is not None:
+            self.srv._httpd.socket.close()
+
+    def test_cron(self):
+        """
+        Test that the cron functions are called properly.
+        """
+        thread = Thread(target=self.srv.start)
+        thread.start()
+        sleep(12)
+        self.srv._httpd.shutdown()
+        with lock:
+            self.assertEqual(2, cron1called)
+            self.assertEqual(3, cron2called)
+        # Make sure the cron threads were stopped
+        sleep(5)
+        with lock:
+            self.assertEqual(2, cron1called)
+            self.assertEqual(3, cron2called)
diff --git a/templates/admin_all.html b/templates/admin_all.html
index 56dba36..b637cc7 100644
--- a/templates/admin_all.html
+++ b/templates/admin_all.html
@@ -8,6 +8,15 @@
         <label for="admin-myaccount-email">E-Mail: </label>
         <input id="admin-myaccount-email" type="text" name="email" value="{% if authuser.email is not none %}{{ authuser.email }}{% endif %}" /><br/>
 
+        <label for="admin-myaccount-receipt-pref">Receipts: </label>
+        <select id="admin-myaccount-receipt-pref" name="receipt_pref">
+            {% for pref in receipt_preference_class %}
+            <option value="{{ pref.value }}" {% if authuser.receipt_pref == pref %} selected="selected" {% endif %}>{{ pref.human_readable }}</option>
+            {% endfor %}
+        </select>
+        {% if config_smtp_enabled != '1' %}Sending receipts is disabled by your administrator.{% endif %}
+        <br/>
+
         <label for="admin-myaccount-ismember">Member: </label>
         <input id="admin-myaccount-ismember" type="checkbox" disabled="disabled" {% if authuser.is_member %} checked="checked" {% endif %}/><br/>
 
diff --git a/templates/moduser.html b/templates/moduser.html
index 187f4f4..894d198 100644
--- a/templates/moduser.html
+++ b/templates/moduser.html
@@ -20,6 +20,15 @@
         <label for="moduser-account-password">Password: </label>
         <input id="moduser-account-password" type="password" name="password" /><br/>
 
+        <label for="moduser-account-receipt-pref">Receipts: </label>
+        <select id="moduser-account-receipt-pref" name="receipt_pref">
+            {% for pref in receipt_preference_class %}
+            <option value="{{ pref.value }}" {% if user.receipt_pref == pref %} selected="selected" {% endif %}>{{ pref.human_readable }}</option>
+            {% endfor %}
+        </select>
+        {% if config_smtp_enabled != '1' %}Sending receipts is disabled by your administrator.{% endif %}
+        <br/>
+
         <label for="moduser-account-ismember">Member: </label>
         <input id="moduser-account-ismember" name="ismember" type="checkbox" {% if user.is_member %} checked="checked" {% endif %}/><br/>
 
@@ -29,6 +38,9 @@
         <label for="moduser-account-balance">Balance: </label>
         CHF <input id="moduser-account-balance" name="balance" type="number" step="0.01" value="{{ user.balance|chf(False) }}" /><br/>
 
+        <label for="moduser-account-balance-reason">Reason for balance modification: </label>
+        <input id="moduser-account-balance-reason" type="text" name="reason" placeholder="Shows up on receipt" /><br/>
+
         <label for="moduser-account-avatar">
             <img height="150" src="/upload/thumbnails/users/{{ user.id }}.png" alt="Avatar of {{ user.name }}" />
         </label><br/>
diff --git a/templates/receipt.txt b/templates/receipt.txt
new file mode 100644
index 0000000..a047f9c
--- /dev/null
+++ b/templates/receipt.txt
@@ -0,0 +1,26 @@
+
+  ===================================================================
+                            MATEMAT RECEIPT
+  ===================================================================
+
+  User:                      {{ user|safe }}
+  Accounting period:         {{ fdate|safe }}  --  {{ tdate|safe }}
+
+
+  Opening balance:                                       {{ fbal|safe }}
+
+  Transactions:
+  {% for t in transactions %}
+  {% include 'transaction.txt' %}
+  {% endfor %}
+
+                                                         ------------
+  Closing balance:                                       {{ tbal|safe }}
+
+  ===================================================================
+
+  {{ instance_name|striptags }}{% if receipt_id > 1 %}
+  Receipt N° {{ receipt_id|safe }}{% endif %}
+
+  This receipt is only provided for informational purposes and has no
+  legal force.
diff --git a/templates/transaction.txt b/templates/transaction.txt
new file mode 100644
index 0000000..78b3039
--- /dev/null
+++ b/templates/transaction.txt
@@ -0,0 +1,2 @@
+{{ t.receipt_date|safe }}    {{ t.receipt_description.ljust(36)|safe }}  {% if t.receipt_message is none %}{{ t.receipt_value.rjust(8)|safe }}{% else %}
+                       {{ t.receipt_message.ljust(36)|safe }}  {{ t.receipt_value.rjust(8)|safe }}{% endif %}
\ No newline at end of file