SpamAssassin - Use this program to "Unspam" your mailbox(es).
Tricount - Manage and share expenses with friends
MailScanner - MailScanner is a open source email security system design for Linux-based email gateways.
Kittysplit - The easiest way of sharing costs with a group of friends
Rspamd - Rspamd is an advanced spam filtering system that allows evaluation of messages by a number of rules...
ihatemoney - Manage your shared expenses, easily