Twiggi
- A customized version of Twig with additional features, designed to behave like Outlook. [GPL]
- http://www.twiggi.org/

Atmail
- A perl-based feature-rich web email system supporting access via web, WAP, POP3 or IMAP. Fully customizable, with web-admin, scheduler, migration scripts and Unix/Windows technical support. [Commercial]
- http://atmail.com/

XandMail
- Developers of messaging applications technology for companies and organizations.
- http://www.xandmail.com/

Advox Omnigate
- A Windows-based webmail solution for ISP and Corporate. [Commercial]
- http://www.advox.se/eng/index_eng.htm

WING
- Web IMAP NNTP Gateway, an open source Apache/mod_perl based system which allows users to access email held on an IMAP server via any web browser. [Free]
- http://web-imap.sourceforge.net/

Open WebMail
- A perl-based webmail system designed to manage very large mail folder files in a memory efficient way. [GPL]
- http://openwebmail.org/

Caudium Mail (CAMAS)
- Webmail system based on IMHO, designed to run with Caudium Webservers. Designed with the ISP in mind, it's scalable and free to use. [GPL]
- http://caudium.net/camas/

Webmail Pro
- Webmail Pro is a robust, reliable, and feature-packed web-based email client driven by ColdFusion. Webmail Pro offers a whole suite of personalized, database-driven features. [Commercial]
- http://www.mollerus.net/development/webmail/

WebMail
- Provides access to LAN-based email over the Web with most browsers, from a Windows-based server. [Commercial]
- http://www.ssimail.com/WebMail.htm

iNetMail
- A web-based software module for online mail management. It helps you check and organize your Internet mail through your Web Browser, from an IIS server. [Commercial]
- http://www.inetmailonline.com/

Auto-EmailPro
- Simplifies the process of offering free Web-based e-mail. For mod_perl. [Commercial]
- http://buildacommunity.com/autoemail/

WebmailASP
- Multiuser webmail ASP script works like a desktop email client. Includes dynamic tree of folders, attachments, HTML-message display, contact books and search. All information moved/copied from POP3 and stored in database. [Commercial]
- http://www.webmailasp.net/

MailMan
- Full-featured perl based web interface for POP3 email accounts. [Commercial]
- http://www.endymion.com/products/mailman/index.htm

AnyEMail
- Perl program to read/send email from a POP3 email account. [Commercial]
- http://www.netbula.com/anyemail/

EMU Mail
- Programs to provide a web interface for accessing a POP3 and IMAP email account. Free version includes banner ads, paid versions don't. [Commercial]
- http://emumail.com/

Acmemail
- POP3 webmail software written in Perl, with full support for MIME. [GPL]
- http://www.astray.com/acmemail/

NetWin WebMail
- Web interface software for accessing POP3 and IMAP email accounts. Available for a range of platforms. [Commercial]
- http://www.netwinsite.com/webmail/