Import Postfix 2.9.5. Major changes since version 2.8.x:
- Support for long, non-repeating, queue IDs (queue file names). The
  main benefit of non-repeating names is simpler logfile analysis. See
  the description of "enable_long_queue_ids" in postconf(5) for
  details.
- Memcache client support, and support to share postscreen(8) and
  verify(8) caches via the proxymap server. Details about memcache
  support are in memcache_table(5) and MEMCACHE_README.
- Gradual degradation: if a database is unavailable (can't open, most
  read or write errors) a Postfix daemon will log a warning and
  continue providing the services that don't depend on that table,
  instead of immediately terminating with a fatal error. To terminate
  immediately when a database file can't be opened, specify
  "daemon_table_open_error_is_fatal = yes".
- Revised postconf(1) command. It warns about unused parameter
  name=value settings in main.cf or master.cf (likely mistakes),
  understands "dynamic" parameter names such as names that depend on
  the name of a master.cf entry (finally, "postconf -n" shows all
  parameter settings), and it can display main.cf and master.cf in a
  more user-friendly format (postconf -nf, postconf -Mf).
- Read/write deadline support in the SMTP client and server to defend
  against application-level DOS attacks that very slowly write or read
  data one byte at a time.