The stable Postfix release is called postfix-2.5.x where 2=major
release number, 5=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-2.6-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 2.4 and earlier
============================================

If you upgrade from Postfix 2.4 or earlier, read RELEASE_NOTES-2.5
before proceeding.

Incompatible changes with snapshot 20080207
===========================================

According to discussions on the mailing list, too many people are
breaking newly installed Postfix by overwriting the new /etc/postfix
files with versions from an older release, and end up with a broken
configuration that cannot repair itself. For this reason, postfix-script,
postfix-files and post-install are moved away from /etc/postfix to
$daemon_directory.