diff --git a/nixos/modules/services/mail/opensmtpd.nix b/nixos/modules/services/mail/opensmtpd.nix
index 3b493d2015dc..f048a382ca42 100644
--- a/nixos/modules/services/mail/opensmtpd.nix
+++ b/nixos/modules/services/mail/opensmtpd.nix
@@ -48,15 +48,13 @@ in {
 
       serverConfiguration = mkOption {
         type = types.lines;
-        default = "";
         example = ''
           listen on lo
           accept for any deliver to lmtp localhost:24
         '';
         description = ''
           The contents of the smtpd.conf configuration file. See the
-          OpenSMTPD documentation for syntax information. If this option
-          is left empty, the OpenSMTPD server will not start.
+          OpenSMTPD documentation for syntax information.
         '';
       };