diff --git a/mail-server.nix b/mail-server.nix
index bf0331f..d89d6ae 100644
--- a/mail-server.nix
+++ b/mail-server.nix
@@ -182,6 +182,7 @@ in {
           lmtpPort = 24;
           authPort = 5447;
           userdbPort = 5448;
+          dkimPort = 5734;
           mkUserMap = username:
             let uid = config.users.users."${username}".uid;
             in "${toString uid}:${toString uid}";