atMail is a fully-featured WebMail server, allowing users to send and receive email via a Web browser or WAP device. It has full support for IMAP/POP3 mailboxes, and an optional email-server mode that uses Exim as the MTA. Features include a scheduler, MySQL backend support, spell-check, addressbook, user preferences, multiple accounts, Spamassassin support, migration scripts from other mail servers, a customizable interface, an attractive DHTML interface, an optional group Calendar/Addressbook, an Outlook 2000/2003 plugin to sync Contacts/Tasks/Calendar data between a desktop client and Webmail.
EMEXIS webmail is a Webmail application based on SquirrelMail.
MailBee WebMail Lite PHP
MailBee WebMail Lite PHP is an AJAX webmail application with skins support. It lets users receive, view, manage, compose, and send email through a Web interface. POP3 and SMTP are supported. It supports multiple attachments, ESMTP, skins, and Web-based administration. It correctly displays HTML mail and is easy to install.
NS WebMail is a web-based application allowing users to retrieve and send mails using SMTP and POP3. It does not download permanently mails from POP3 servers, avoiding mail duplication. It has been designed to be "light and simple".
Tellmatic is a tool to manage and create newsletters for personalized mailing or mass mailing. Addresses and newsletters are stored in groups to handle different user groups and thousands of addressses at a time.