Sendmail::PMilter is a mail filtering API implementing the Sendmail
milter protocol in pure Perl.  This allows Sendmail servers (and perhaps
other MTAs implementing milter) to filter and modify mail in transit
during the SMTP connection, all in Perl.

It should be noted that PMilter 0.90 and later is NOT compatible with
scripts written for PMilter 0.5 and earlier.  The API has been reworked
significantly, and the enhanced APIs and rule logic provided by PMilter
0.5 and earlier has been factored out for inclusion in a separate package
to be called Mail::Milter.

So, in short, this package should be regarded as a drop-in replacement
for Sendmail::Milter, with only some very minor API extensions related
to the milter protocol itself.  (Sendmail::PMilter includes a wrapper
module named Sendmail::Milter to allow old milter scripts to continue
working as-is with this package.)