Quote from the RELEASE_NOTES file:
Incompatible changes with snapshot-20001121
===========================================
If this release does not work for you, you can go back to a previous
Postfix version without losing your mail, subject to the "incompatible
changes" listed for previous Postfix releases below.
Major changes with snapshot-20001121
====================================
Support for RedHat Linux 7.0. On RedHat Linux 7.0, you must install
the db3-devel RPM before you can compile the Postfix source code.
The mailbox_transport feature works again. It was broken when the
"require_home_directory" feature was added.
More general virtual domain support. Postfix now supports both
Sendmail-style virtual domains and Postfix-style virtual domains.
Details and examples are given in the revised virtual manual page.
- With Sendmail-style virtual domains, local users/aliases/mailing
lists are visible as localname@virtual.domain. This is convenient
if you want to host mailing lists under virtual domains.
- With Postfix-style virtual domains, local users/aliases/mailing
lists are not visible as localname@virtual.domain. Each virtual
domain has its own separate name space.
More general "soft bounce" feature. Specify "soft_bounce = yes"
in main.cf to prevent the SMTP server from bouncing mail while you
are testing configurations. Until this release the SMTP server was
not aware of soft bounces.
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