This is the Postfix 3.6 (experimental) release.

The stable Postfix release is called postfix-3.5.x where 3=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-3.6-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.

If you upgrade from Postfix 3.4 or earlier, read RELEASE_NOTES-3.5
before proceeding.

License change
---------------

This software is distributed with a dual license: in addition to the
historical IBM Public License 1.0, it is now also distributed with the
more recent Eclipse Public License 2.0. Recipients can choose to take
the software under the license of their choice. Those who are more
comfortable with the IPL can continue with that license.

Major changes with snapshot 20200509
====================================

The threadsafe resolver API (res_nxxx() calls) is now the default,
not because the API is threadsafe, but because new features are
being added there.

To build old style, build with:

    make makefiles CCARGS="-DNO_RES_NCALLS..."

This is also the default for systems that are known not to support
the threadsafe resolver API, such systems that use libc-musl.
