Change SQL Password is a great plugin for Squirrelmail if you store your user accounts in a SQL database. This plugin provides a way for end users to change their passwords.
Reference: http://www.squirrelmail.org/plugin_view.php?id=117
Installation Notes
This plugin requires the Compatibility Plugin be installed and corresponding Compatibility Plugin be applied to Squirrelmail.
PHP support for Pear-DB must also be installed. One method is to install via a package.
In RH/Fedora Distros these packages are called php-pear-DB and php-pear
Pear-DB format is as follows:
'mysql://SQLuser:MySQL_Password@localhost/mail'
mysql:// = type of Database to connect to (In this case MySQL) SQLuser = User with access to the Database MySQL_Password = Password for Above MySQL User localhost = Server Address, (can also be an IP address or Hostname) /mail = Name of the Database(Schema) you are connecting to