diff --git a/roles/prometheus/templates/blackbox.yml b/roles/prometheus/templates/blackbox.yml
index 89125d8..6a2d77f 100644
--- a/roles/prometheus/templates/blackbox.yml
+++ b/roles/prometheus/templates/blackbox.yml
@@ -131,6 +131,20 @@ modules:
         - expect: "^250 .*$"
         - send: "QUIT"
 
+  submission_starttls:
+    prober: tcp
+    timeout: 2s
+    tcp:
+      {% if blackbox_prefer_ipv4 -%}
+      preferred_ip_protocol: ip4
+      {% endif -%}
+      query_response:
+        - starttls: true
+        - expect: "^220 .*SMTP .*$"
+        - send: "HELO {{ blackbox_smtp_name }}"
+        - expect: "^250 .*$"
+        - send: "QUIT"
+
   imap:
     prober: tcp
     timeout: 2s