OfflineIMAP

"OfflineIMAP is a tool to simplify email reading.It allows you to read the same mailbox frommultiple computers and ensures that your changeswill be automatically reflected on all computers.You can use various mail clients to read a singlebox or read mail while offline with fullsynchronization when you reconnect. You can readIMAP mail with readers that lack IMAP support(same goes for SSL). OfflineIMAP's multithreadedsynchronization algorithm performs between 10 and60 times faster than many mail readers' internalIMAP support, and it can be used even with mailreaders that support IMAP already. There are fiveavailable user interface modules, includingscripted execution, an interactive terminalinterface, and GUI interfaces." (Description on Freshmeat)