diff --git a/roles/prometheus/templates/blackbox.yml b/roles/prometheus/templates/blackbox.yml
index 34fb3bd..455f5a8 100644
--- a/roles/prometheus/templates/blackbox.yml
+++ b/roles/prometheus/templates/blackbox.yml
@@ -126,6 +126,8 @@ modules:
       {% endif -%}
       query_response:
         - expect: "^220 .*SMTP .*$"
+        - send: "STARTTLS"
+        - expect: "^220.*TLS.*"
         - starttls: true
         - send: "HELO {{ blackbox_smtp_name }}"
         - expect: "^250 .*$"