Extract from the RELEASE_NOTES file:
Incompatible changes with snapshot-20001210
===========================================
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.
When delivering to /file/name (as directed in an alias or .forward
file), the local delivery agent now logs a warning when it is unable
to create a /file/name.lock file. Mail is still delivered as before.
The "sun_mailtool_compatibility" feature is going away (a compatibility
mode that turns off kernel locks on mailbox files). It still works,
but a warning is logged. Instead of using "sun_mailtool_compatibility",
specify the mailbox locking strategy as "mailbox_delivery_lock =
dotlock".
The Postfix SMTP client now skips SMTP server replies that do not
start with "CODE SPACE" or with "CODE HYPHEN" and flags them as
protocol errors. Older Postfix SMTP clients silently treated "CODE
TEXT" as "CODE SPACE TEXT", i.e. as a valid SMTP reply.
This snapshot does not yet change default relay settings. That
change alone affects a dozen files, most of which documentation.
This may be an incompatibility with some people's expectations,
but such are my rules - between code freeze and release no major
functionality changes are allowed.
Several interfaces of libutil and libglobal routines have changed.
This may break third-party code written for Postfix. In particular,
the safe_open() routine has changed, the way the preferred locking
method is specified in the sys_defs.h file, as well as all routines
that perform file locking. When compiling third-party code written
for Postfix, the incompatibilities will be detected by the compiler
provided that #include file dependencies are properly maintained.
Major changes with snapshot-20001210
====================================
This snapshot includes bugfixes that were already released as
patches 12 and 13 for the 19991231 "stable" release:
- The queue manager could deadlock for 10 seconds when bouncing
mail under extreme load from one-to-one mass mailings.
- Local delivery performance was substandard, because the per-user
concurrency limit accidentally applied to the entire local
domain.
The mailbox locking style is now fully configurable at runtime.
The new configuration parameter is called "mailbox_delivery_lock".
Depending on the operating system type, mailboxes can be locked
with one or more of "flock", "fcntl" or "dotlock". The command
"postconf -l" shows the available locking styles. The default
mailbox locking style is system dependent. This change affects
all mailbox and all "/file/name" deliveries by the Postfix local
delivery agent.
The new "import_environment" and "export_environment" configuration
parameters now provide explicit control over what environment
variables Postfix will import, and what environment variables
Postfix will pass on to a non-Postfix process. This is better than
hard-coding my debugging environment into public releases.
The "mailbox_transport" and "fallback_transport" parameters now
understand the form "transport:nexthop", with suitable defaults
when either transport or nexthop are omitted, just like in the
Postfix transport map. This allows you to specify for example,
"mailbox_transport = lmtp:unix:/file/name".
The MYSQL client now supports server connections over UNIX-domain
sockets. Code provided by Piotr Klaban. See the file MYSQL_README
for examples of "host" syntax.
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