diff --git a/roles/ispmail-dovecot/files/10-ssl.conf b/roles/ispmail-dovecot/files/10-ssl.conf
index 3ad921d..47ca04c 100644
--- a/roles/ispmail-dovecot/files/10-ssl.conf
+++ b/roles/ispmail-dovecot/files/10-ssl.conf
@@ -3,7 +3,7 @@
 ##
 
 # SSL/TLS support: yes, no, required. <doc/wiki/SSL.txt>
-ssl = yes
+ssl = required
 
 # PEM encoded X.509 SSL/TLS certificate and private key. They're opened before
 # dropping root privileges, so keep the key file unreadable by anyone but