disable plaintext auth

templates/conf.d/10-auth.conf.j2

@@ -7,7 +7,7 @@
 # matches the local IP (ie. you're connecting from the same computer), the
 # connection is considered secure and plaintext authentication is allowed.
 # See also ssl=required setting.
-#disable_plaintext_auth = yes
+disable_plaintext_auth = yes
 
 # Authentication cache size (e.g. 10M). 0 means it's disabled. Note that
 # bsdauth, PAM and vpopmail require cache_key to be set for caching to be used.