Perdition is a Mail Proxy used to distribute POP and IMAP requests between multiple backends, also converting between protocols.
The perdition homepage can be found here - and to quote from its website -
"Perdition is a POP3, IMAP4 and managesieve proxy server. It is able to handle both plain-text and SSL/TLS encrypted connections, and redirect users to a real-server based on a database lookup. Perdition supports modular based database access. ODBC, MySQL, PostgreSQL, GDBM, POSIX Regular Expression and NIS modules ship with the distribution. The API for modules is open allowing arbitrary modules to be written to allow access to any data store.
Perdition has many uses. Including, creating large mail systems where an end-user's mailbox may be stored on one of several hosts, integrating different mail systems together, migrating between different email infrastructures, and bridging plain-text and SSL/TLS services. It can also be used as part of a firewall. The use of perdition to scale mail services beyond a single box is discussed in high capacity email. "
