diff --git a/nixos/modules/services/mail/dovecot.nix b/nixos/modules/services/mail/dovecot.nix
index 7d7ba6b867a5..8548b3107346 100644
--- a/nixos/modules/services/mail/dovecot.nix
+++ b/nixos/modules/services/mail/dovecot.nix
@@ -296,6 +296,20 @@ in
 
     enableLmtp = mkEnableOption "starting the LMTP listener (when Dovecot is enabled)";
 
+    hasNewUnitName = mkOption {
+      type = types.bool;
+      default = true;
+      readOnly = true;
+      internal = true;
+      description = ''
+        Inspectable option to confirm that the dovecot module uses the new
+        `dovecot.service` name, instead of `dovecot2.service`.
+
+        This is a helper added for the nixos-mailserver project and can be
+        removed after branching off nixos-25.11.
+      '';
+    };
+
     protocols = mkOption {
       type = types.listOf types.str;
       default = [ ];