Well "kmail 2" does not exist - it was a working name for the version after kmail 2 now tey version number is bundeld with kdepim. So the newest version available is kdepim 4.14. In my eyes, we should let kmail 1 (everything before 4.11 is called so) leave behind and look at the new version, that is available at debian sid. The old version that sata recompield for the newest kde version is a very nice gift, but there will be no bugfixes or any improvments - it is a dead hores. I am a very happy kmail user and developer.