Fetchmail is a full-featured, robust, well-documented remote-mail retrieval and forwarding utility intended to be used over on-demand or permanent dynamic-address TCP/IP links (such as SLIP or PPP connections). It supports every remote-mail protocol now in use on the Internet: POP3, IMAP4r1, ETRN
... [More], and ODMR, all with various authentication variants, and TLS/SSL security with certificate verification.
Fetchmail retrieves mail from remote mail servers and forwards it via SMTP, LMTP, or to a local delivery agent. Mail can then be read by normal mail software such as mutt or alpine. This setup allows all your system MTA's filtering, forwarding, and aliasing facilities to work just as they would on normal mail. [Less]
Fast and scalable email services based on storage of messages in a database.
Robust support for IMAP4r1, POP3, LMTP, MANAGESIEVE.
Fully normalised decomposition of messages into headers and mimeparts.
Mimeparts are stored in a single-instance paradigm, preventing unnecessary duplication.
Also supports a scalable connection pool to limit the database connection load under high concurrencies. [Less]
Archiveopteryx is a mail server system optimised for long-term storage and heavy access. It comprises a set of server programs that provide access to mail stored in a relational database (PostgreSQL). It runs on Linux, FreeBSD, NetBSD, OpenBSD and Mac OS X.