Log Message:
  Update to version 2.53.
  This also closes PR pkg/21114 (thanks to Todd Vierling for dynamic PLIST)

  Most serious bugs since release of SA 2.50 fixed (hence the 'long'
  delay for the Pkgsrc package).

  Dependence on procmail removed. You still need a mail delivery agent
  but procmail is only a recommendation, not a prerequisite.

  Runs on Solaris (somewhat tested on Solaris 8, feedback welcome).

  Includes some SSL support for spamc/spamd. Not yet recommended due to
  lurking bug(s) (SA bugzilla ID 1751).

  Uses Perl module DB_File now instead of NDBM_File. This changes the
  name and format of the auto-whitelist database  ('auto-whitelist'
  instead of 'auto-whitelist.db' on NetBSD).

  ! This release adds/changes/removes configuration options, PLEASE use !
  ! 'perldoc Mail::SpamAssassin::Conf' and make  sure your mail         !
  ! configuration still works as expected.                              !

==========================================================================

Changes since 2.52:

- corruption of Bayes db where nspam/nham was getting zeroed, fixed.

- Bayes now has much lower lock timeouts for opportunistic expiry
  and auto-learning, to avoid overloading busy servers with an expiry
  run.  (This may result in occasional "lock failed" messages in the
  syslog while you're doing manual sa-learn ops, but those are
  not serious; it just means that an auto-learn could not take place
  because the dbs were opened by you in another process.)

- NDBM_File does not provide an EXISTS method, worked around.

- BSMTP support (spamc -B) fixed.

- Bayes allowed the user to 'forget' messages they hadn't learned.

- sa-learn broken when installed in a non-standard location.

- spamc was failing to dump message if out of memory.

- add-all-addrs-to-blacklist was a no-op, fixed.

- syslog-socket support was broken, fixed.

- sslspamc compilation fixed.

- SIGCHLD handling in spamd was causing an ugly warning on Red Hat 8.

- user_prefs were left world-writable after auto-whitelist use.

- Razor was zeroing %ENV; protected against this.

- some test failures on 5.005 and with Razor fixed; some tests were
  also still using the user's Bayes dbs.

- Windows portability fix in new Bayes journal code.

- dialup_codes now a privileged setting.

- clean PATH env variable immediately upon spamd start; fixed problem
  with taint mode failures when getting hostname in Perl 5.005.

- NetBSD: fixed SSL support, spamd start script.

- single-Received-header mails were not getting DNSBL checks.

- some doco fixes.

Changes since 2.51:

  - bug 1664: expiry imposed way too much load when a single
    site-wide Bayes db was used, fixed
  - bug 1672: a typo in a backported patch for 2.51 caused Bayes to
    sometimes not unlock the db, fixed
  - INSTALL now strongly recommends using DB_File
  - some NetBSD support fixes
  - bug 1601: option --syslog-socket wasn't implemented
  - bug 1260: corrected description of --nocreate-prefs option

Changes since 2.50:

  - Bayes locking and concurrency issues fixed
  - Bayes expiration was not working; fixed
  - spamd was not enabling Bayes after auto-learning without restart;
    fixed
  - safer way to attach spams, for broken mail clients, using 'report_safe
    2'
  - a few doco cleanups

Main changes since 2.4x:

- Bayesian filtering, using a Bayesian-style form of probability-analysis
  classification.  This uses an algorithm based on the one detailed in
  Paul Graham's 'A Plan For Spam' paper, along with aspects taken from
  Graham Robinson's work, and the chi-combining technique developed by the
  SpamBayes project.

- Auto-learning.  This trains the Bayesian filter automatically, based on
  the results from traditional SpamAssassin diagnosis.   It uses a set of
  heuristics and separate thresholds to ensure (as much as is possible)
  that it trains on guaranteed non-spam and spam.   Old, unused tokens are
  automatically expired.

- much-improved rule set.  A whole new set of rules based on Message-Id
  analysis is now in place, which accurately detects forged headers from
  a wide range of spamware.   Many inaccurate rules have been dropped.
  HTML tests much improved, with a set to detect image-only spam.

- new default format for detected-spam messages; the message is
  encapsulated as a MIME part, with a preview and the spam report
  in the main part of the message.

- Score sets.  Based on whether you are using just SpamAssassin rules,
  adding network tests, and using a trained Bayesian database,
  SpamAssassin will use a set of scores appropriately to gain the
  maximum degree of accuracy.

- Italian, Polish, Spanish, French and German rule sets and translations.

- Much improved reliability with spamd.  The problems with signals
  have been cleared up thanks to a pipe-based child tracking system,
  and all spamd-hanging bugs reported have proved unreproducable.

- Unicode problems with Red Hat 8 and perl 5.8 fixed.   Works on Perl
  5.005, 5.6.x, and 5.8.x.

- Taint-safe.  SpamAssassin runs with perl's taint-checking enabled for
  better security.

- Razor 1 support is now officially deprecated.

- "spamc -c" was not working, fixed.  This fix required increasing the
  revision of the spamd protocol; only difference is that now more than
  one protocol header can appear in the reply from spamd.

- all fixes from 2.44 included.