diff --git a/nixos/modules/services/mail/postfix.nix b/nixos/modules/services/mail/postfix.nix
index 244ce49ee63b..f842a219910d 100644
--- a/nixos/modules/services/mail/postfix.nix
+++ b/nixos/modules/services/mail/postfix.nix
@@ -853,7 +853,8 @@ in
         smtpd_tls_cert_file = cfg.sslCert;
         smtpd_tls_key_file = cfg.sslKey;
 
-        smtpd_tls_security_level = "may";
+        smtpd_tls_security_level = lib.mkDefault "may";
+
       };
 
       services.postfix.masterConfig = {