diff --git a/mail-server/assertions.nix b/mail-server/assertions.nix
index 374c17b..1885af4 100644
--- a/mail-server/assertions.nix
+++ b/mail-server/assertions.nix
@@ -5,7 +5,7 @@
 }:
 
 let
-  mailserverRelease = "25.11";
+  mailserverRelease = "26.05";
   nixpkgsRelease = lib.trivial.release;
   releaseMismatch =
     config.mailserver.enableNixpkgsReleaseCheck && mailserverRelease != nixpkgsRelease;