I prefer avoid working on google products are they are becoming more and more commercial and definitely have privacy concerns.
Google Apps for business, after the major commercialization left many companies no where unless they pay google. Bandwidth, Diskspace & Uptime is not an issue for any corporate intranet website. We just need a slick email client to do a smooth migration.
After little research here are my findings.
There are some plugins available to extend more functions.
IMP is currently at version 5 and requires Horde 4. It adds new features like a new mobile frontend for smartphones, much improved AJAX frontend with new vertical layout
Gwebmail is an ajax powered webmail system with an interface similar to Gmail
It is entirely written in PHP and uses MySQL to store messages
It comes with fremium model, and 10 users are free.
Last Update: 2009-07-16
AtMail is an open source webmail client written in PHP. We aim to provide a elegant Ajax webmail client for existing IMAP mailservers, with less bloat and a focus on an intuitive, simple user interface. They also have a commercial version of Atmail. Commercial version interface looks very promising.
AfterLogic WebMail Lite PHP
Last Update: 2011-12-06
Also compare with commercial
- Supports SMTP/IMAP/POP3/XMail protocols; MySQL or MS SQL database backend
- Ajax driven interface
- Address Book
- Skins and translations (including RTL rendering)
- cPanel integration
HiveMail now provides even more features and a revamped UI ! Amongst a stunning File Storage implementation which allows to add attachments from/to Storage, we have implemented the world’s firstQuickview / Quickreply System – a really slick and easy way to view/reply messages !
Last Update: 2012-08-20
Hastymail is a fast, secure, rfc-compliant, cross-platform IMAP/SMTP client application written in PHP providing a clean web interface for sending and reading E-mail.
Beta Last Update: 2012-08-27
T-dah webmail project based on uebimiau with new updates, template skins, filters, chat and calendar. T-dah Webmail is small, efficient, very easy to install and is always being improved.
Last Update: 2011-09-19
SquirrelMail is a PHP-based Web email client. It includes built-in pure PHP support for IMAP and SMTP, and renders all pages in pure HTML 4.0 for maximum compatibility across browsers. It has strong MIME support and a flexible plugin system. Interface looks old age of 1960s. But provide ensignia (following) better themes for it. Comments says code structure is good to incorporate and customize.
SquirrelOutlook is a standards-based webmail package written in PHP4 (Squirrelmail). It includes built-in pure PHP support for the IMAP and SMTP protocols, and all pages render in pure HTML 4.0 for maximum compatibility across browsers.
Emexis-webmail skin squirremail
emexis-webmail is a skin for the well-known Squirremail The intention of this project is to create more friendly interface for the End User
Ensignia (Powered by Squirrelmail)
Another squirrelmail fork, but commerical.
Last Update: 2012-08-14
NOCC is a simple and fast Webmail client which can handle POP3, SMTP, and IMAP servers. It is written with PHP5 (uses sessions), has low requirements (no database, frames). Features multi-language support, MIME attachments, displays HTML messages.
There were few others like popper, v-webmail etc, but were of very low quality interface so i skipped them in this extract.
Hope it is useful for businesses.