K-9 Mail – Advanced Email for Android

Read/sync your IMAP mailboxes [Python]

http://imapfw.offlineimap.org IMAP/mail framework under MIT licence and written in Python

Mail App with integrated OpenPGP encryption

C++ Mail manager

Forward mail from gmail IMAP to a callback URL, simply.

Program to securely send and receive HTML e-mails (and of course normal text e-mails too)