POPauthd is a Perl-based daemon that uses POP to
authorize connecting hosts for SMTP relaying. It
is particularly useful to authenticate roaming
users with IP addresses that change often. The
daemon runs in the background, watching the syslog
for successful POP logins. When it sees one it
enters the IP in sendmail's access database,
giving the host authorization to relay through the
server. The entries can be expired after a
prescribed, configurable period of time with a
companion script run via crontab.
