The stable Postfix release is called postfix-2.3.x where 2=major release number, 3=minor release number, x=patchlevel. The stable release never changes except for patches that address bugs or emergencies. Patches change the patchlevel and the release date. New features are developed in snapshot releases. These are called postfix-2.4-yyyymmdd where yyyymmdd is the release date (yyyy=year, mm=month, dd=day). Patches are never issued for snapshot releases; instead, a new snapshot is released. The mail_release_date configuration parameter (format: yyyymmdd) specifies the release date of a stable release or snapshot release. Incompatibility with Postfix 2.2 and earlier ============================================ If you upgrade from Postfix 2.2 or earlier, read RELEASE_NOTES-2.3 before proceeding. Incompatible changes with Postfix snapshot 20060806 =================================================== Postfix no longer announces its name in delivery status notifications. Users believe that Wietse provides a free help desk service that solves all their email problems.