Configure Squirrel webmail (June 2011)
The squirrelmail configuration is not difficult and well explained on the squirrel web site (http://squirrelmail.org/).
I don't want to have anything growing in the / partition, so I move any data repository to /data (my very large partition). Here there are two squirrelmail data directories, that probably do not ever become hudge (but for attachements, who knows?), data and attach. I locate them in /dta/srv/www/squirrell (so out of the web server normal access).
These folders have to be wwwrun:www (openSUSE apache2 user:group) and chmod 0733 (writable by anybody but readable by nobody). This makes it impossible for the web server to remove any of theses files. The config files (in data) are known name and can be overwritten, but not the attach files. If you think the attached files may become hudge, you may need a cron job to remove too big or too old files.
This config is created by a perl script in your squirrel folder config subfolder (config/.conf.pl). In this config utility, I only change the domain name (dodin.org, for me) and the two data/attach folders.
As advised by squirrel, I keep the full version name of squirrel and add a link to it (ln -s squirrelXXXX webmail or squirrel). Thgis makes upgrade very simple: install the new version, configure it and voilà (no data is stored in the squirrel folder).
Once configured, visit the page <squirellURL>/src/configtest.php to verify your config.
I had to ass some php modules (gettext, mbstring, iconv). I don't find the recode module, but it don't seems necessary.
Squirrelmail is a php module, so depends on the php defaults. I had to change them a bit.
In /etc/php5/apache/php.ini, I changed
memory_limit = 512M post_max_size = 80M upload_max_filesize = 200M
(it's nice to have much RAM and HDD size :-)