OfflineIMAP is a tool to synchronize IMAP and Maildir mailboxes which is very
fast due to its multithreaded synchronization algorithm. It offers several
user interfaces and is generally very configurable providing a great number of
settings for controlling its behavior, tuning performance. Specifically, there
are several sophisticated and flexible mechanisms for determining the list of
maiilboxes to synchronize. Furthermore, it supports internal or external
automation, SSL and PREAUTH tunnels, offline (or "unplugged") reading, and a
variety of esoteric IMAP features for compatibility with the widest variety of
IMAP servers. OfflineIMAP is designed for safety in terms of avoiding the loss
of mails under any circumstances.