popa3d is a POP3 daemon by Solar Designer.
In order, its design goals are:
1. Security (to the extent that is possible with POP3 at all, of course).
2. Reliability (again, as limited by the mailbox format and the protocol).
3. RFC compliance (slightly relaxed to work with real-world POP3 clients).
4. Performance (limited by the more important goals above)
