Class to handle mail queue managment.
Wrapper for PEAR::Mail and PEAR::DB (or PEAR::MDB/MDB2).
It can load, save and send saved mails in background
and also backup some mails.

The Mail_Queue class puts mails in a temporary container,
waiting to be fed to the MTA (Mail Transport Agent),
and sends them later (e.g. a certain amount of mails
every few minutes) by crontab or in other way.

WWW: https://pear.php.net/package/Mail_Queue