SquirrelMail is a standards-based webmail package written in PHP. It includes built-in pure PHP support for the IMAP and SMTP protocols, and all pages render in pure HTML 4.0 (with no JavaScript required) for maximum compatibility across browsers. It has very few requirements and is very easy to configure and install. SquirrelMail has all the functionality you would want from an email client, including strong MIME support, address books, and folder manipulation.
SquirrelMail is stable enough to use in a production system. It is, in fact, already used in several production systems around the world, handling thousands of users per system. There might be some bugs – no project is perfect – but they are most likely minimal. We test pretty thoroughly before releasing a version marked as “stable”.
SquirrelMail is known to scale well for large installations with thousands of users. It’s recommended to have a lot of free memory available at the web server. Another common problem with larger systems is the connections per minute limitation. Suggested reading is Optimizing SquirrelMail, SquirrelMail performance, and the speed section in the wiki.
There are only two requirements for SquirrelMail:
* A web server with PHP installed. PHP needs to be at least 4.1.0. PHP 4, PHP 5 and PHP 6 are all supported.
* Access to an IMAP server which supports IMAP 4 rev 1.
It doesn’t really matter what OS or web server you use, as long as the combination thereof supports PHP in a stable way. Read the instructions and suggestions in the PHP documentation to see what they recommend.
If you’re building your mail system from scratch, it might be a good idea to install and test all components one by one. If you install everything at once and things don’t work, the troubleshoting will be more complex. If the web server doesn’t work there’s not much point in trying to install PHP, for instance. Make sure that everything is working before trying to install SquirrelMail.
If you want to know more about the SquirrelMail please visit http://squirrelmail.org/
