This is the Postfix 3.2 (experimental) release.

The stable Postfix release is called postfix-3.1.x where 3=major
release number, 1=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-3.2-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.

If you upgrade from Postfix 3.0 or earlier, read RELEASE_NOTES-3.1
before proceeding.

Major changes with snapshot 20160527
====================================

Postfix cidr tables now support if..endif, and pattern negation
with "!", just like regexp and pcre tables. The if..endif can speed
up lookups by skipping over irrelevant patterns, and can make rule
maintenance easier because rules for a network can now be placed
inside if..endif.  See the cidr_table(5) manpage for syntax details.