Ledmail is a small mail checking utility that utilises the keyboard LEDs (caps, num, and scroll lock) to indicate when new mail has arrived. The LEDs are made to flash in an answerphone-like manner to indicate the number of new messages that are present in given mail servers. Each LED can be given a separate list of mail servers to poll, and the total number of new messages on those servers will determine how many times the LED will flash. Errors in checking mail servers cause the LEDs to flash in an inverted state, or to stay on. Ledmail can check both POP3 and IMAP4 mail servers.
Heirloom mailx (formerly known as "nail") is derived from Berkeley Mail and provides the functionality of the System V and POSIX mailx commands. Additional features include support for MIME, IMAP (including caching and disconnected use), POP3, SMTP, S/MIME, international character sets, maildir folders, message threading, powerful search methods, scoring, and a Bayesian junk mail filter. Mailx can be used as a mail batch language in nearly the same way as it is used interactively. It can thus act as a mailbox filter, can fetch mail from remote accounts, and can send files as attachments.
Netbiff is an advanced version of the traditional biff (a mail-checking program). Features include BSD mailbox and IMAP4 support, a backend plug-in system (for other protocols), arbitrary numbers of backends, pluggable interfaces (GTK and text-based), and arbitrary actions on biff.
Perdition is a fully featured POP3 and IMAP4 proxy server. It is able to handle both SSL and non-SSL connections and redirect users to a real-server based on a database lookup. Perdition supports modular based database access. The distribution ships with modules for ODBC, MySQL, PostgreSQL, GDBM, POSIX Regular Expression, and NIS. The API for modules is open, allowing abitary modules to be written to allow access to any data store. Perdition can be used to create large mail systems where an end-user's mailbox may be stored on one of several hosts, to integrate different mail systems together, to migrate between different email infrastructures, and to bridge plain-text, SSL, and TLS services. It can also be used as part of a firewall.
pm2imap.pl is a perl script that will convert Pegasus Mail 3+ mailfolders (and trays) to Unix mbox format in the same Folder structure as your tray structure. This allows you to read your mail via IMAP instead of locally via the filesystem, which allows for "remote" reading of your mail.
pwcheck_mysql is a authentication module for the Cyrus IMAP server. Currently the Cyrus IMAP server only supports kerberos, /etc/passwd and ldap (via Clayton Donely's pwcheck_ldap module). Now with pwcheck_mysql, you can use a MySQL database to authenticate your IMAP users. This code has been tested for many months and seems to work fairly well.
qmail-ldap is an extension to stock qmail-1.03 to get all user account information from an LDAP database. Its primary target is POP toasters with thousands to millions of users, such as in ISP, FreeMail, and Corporate environments. It features full SMTP/POP3/IMAP server clustering for scaling and high availablity. Additionally there are state-of-the art spam filters, TLS SMTP encrytion, and mailbox quotas. A migration path for Netscape Messenger and Software.com's Post.Office installations is provided.
OpenGroupware.org is a set of applications for contact, appointment, project, and content management. It is comparable to Exchange and SharePoint. It is accessible using Web interfaces or using local clients via WebDAV, GroupDAV, and CalDAV. Custom applications can be developed using the XML-RPC API. OpenGroupware.org runs on almost every GNU/Linux system.