getmail is intended as a simple, secure, and reliable replacement for fetchmail. It retrieves email (either all messages, or only unread messages) from one or more POP3, SPDS, or IMAP4 servers (with or without SSL) for one or more email accounts, and reliably delivers into qmail-style Maildirs, mboxrd files, or through external MDAs (command deliveries) specified on a per-account basis. getmail also has excellent support for domain (multidrop) mailboxes, including delivering messages to different users or destinations based on the envelope recipient address.
Mahogany is a GUI email client for the X11/Unix, Windows, and Mac platforms. It supports a wide range of Internet protocols (IMAP4, POP3, ESMTP, NNTP) and encrypted communications using SSL, includes full MIME support, and aims to be fully standard-compliant. It allows the use of unlimited number of servers, supports filters and identities, and offers optional HTML viewing and much more.
OfflineIMAP is a tool to simplify email reading. It allows you to read the same mailbox from multiple computers and ensures that your changes will be automatically reflected on all computers. You can use various mail clients to read a single box or read mail while offline with full synchronization when you reconnect. You can read IMAP mail with readers that lack IMAP support (same goes for SSL). OfflineIMAP's multithreaded synchronization algorithm performs between 10 and 60 times faster than many mail readers' internal IMAP support, and it can be used even with mail readers that support IMAP already. There are five available user interface modules, including scripted execution, an interactive terminal interface, and GUI interfaces.
Hep Message Server is software that transfers messages between different messaging systems. Eventually, it should transparently route messages between email, weblogs, and instant messaging. Currently Hep does one thing: fetches news feeds from Web sites and lets you view them in your email client.
MIR (mobile IMAP reader) is a WAP frontend for reading email from various IMAP accounts. You can browse and read email messages stored in different IMAP mail folders. It is developed with efficiency in mind, and optimised to present all information on a mobile phone in a compact form without any overhead.
Chandler is a standards-based "Note-to-Self Organizer" designed for personal and small-group task management and calendaring. It consists of a desktop application and Chandler Hub, a free sharing service and Web application. You can also download and run your own Chandler Server.