Fetchmail

Fetchmail is a full-featured, robust, well-documented remote-mail retrieval and forwarding utility intended to be used over on-demand TCP/IP links (such as SLIP or PPP connections). It supports every remote-mail protocol now in use on the Internet: POP2, POP3, RPOP, APOP, KPOP, all flavors of IMAP, ETRN, and ODMR. It can even support IPv6 and IPSEC.

Website: http://www.fetchmail.info/

Configuration
poll remote.mailserver.com protocol POP3 username email1@example.net password "password1" is account@localserver.com username email2@example.net password "password2" is account@localserver.com username email3@example.net password "password3" is account@localserver.com ssl sslfingerprint "BF:4E:AA:FB:69:6A:45:16:01:54:64:23:31:89:40:A5"
 * .fetchmailrc