diff --git a/roles/mail_server/molecule/default/group_vars/parameters-optional.yml b/roles/mail_server/molecule/default/group_vars/parameters-optional.yml
index 5adfec2ca8fe74686c034776f6b638495a7d8551..b8cd407acf19330f09793f7fd28dfa6433b63849 100644
--- a/roles/mail_server/molecule/default/group_vars/parameters-optional.yml
+++ b/roles/mail_server/molecule/default/group_vars/parameters-optional.yml
@@ -29,6 +29,7 @@ smtp_rbl:
 mail_postmaster: "webmaster@parameters-optional"
 smtp_allow_relay_from:
   - "10.31.127.22"
+mail_message_size_limit: 20480001
 
 # common
 ca_certificates: