Adding a Squirrelmail plugin is relatively simple. This sample installs the "change_sqlpass" plugin (which requires the "compat" (or compatibility) plugin. First copy the necessary plugins to the server you are installing them onto. A command like:
$ scp plugin timbruce@server:~/download/squirrelmail
Depending on how it's installed, you need to assume the correct user to configure the plugin.
$ sudo su -
On Ubuntu, you need to change to the following directory:
# cd /usr/share/squirrelmail/plugins
Then execute the following command:
# tar -xzvf compatibility-2.0.9-1.0.tar.gz # tar -xzvf change_sqlpass-3.3-1.2.tar.gz
Detemine which version of SquirrelMail you are running (looking at the login page will help). I'm using Ubuntu version 1.4.10a, so I patch using v1.4. Now I can install compatibility using the following command:
# cd /usr/share/squirrelmail/plugins/compatibility/ # patch -p0 < patches/compatibility_patch-1.4.10.diff
After this, configure SquirrelMail.
# cd ../config # ./conf.pl
Go to #8 (Plugins) and install change_sqlpass. (NOTE: I also need to update the plugins/change_sqlpass/config.php file with the appropriate parameters to allow it to update the database.)