Mail client which aims at being “fast, easy to use email client that is suitable for both the inexperienced email user as well as for the most demanding of power users”.
Mailboxes synchronization tool; allows to download email locally; MailDir format supported.
Mail client with tons of features, customization chances, support for IMAP, POP3, multiple storage formats.
MUA written in Ruby; specifically developed for accounts with “a lot of emails”; nice thread-based presentation.