I switched from using squirrelmail to a product called rainloop. Rainloop was relatively easy to install, and is far nicer that squirrelmail. But the basic idea is the same.
A next step for providing mail service for some of my users is a primitive webmail facility. For this I used a product called squirrelmail.
Squirrelmail installs, on fedora, into /usr/share/squirrelmail, with config in /etc/squirrelmail. /usr/share/squirrelmail/config contains a perl script, conf.pl, which provides a simpler configuration experience with explanation of all the somewhat cryptically named fields.
As part of doing this I obtained certificates for all the domains I am hosting – at least all of them over which I have enough control to meet the validation requirements of startssl.com, meaning either I am postmaster or the documentroot of the website is on tarragon. Without this I would have to choose between not encrypting the mail, or having the user have to put up with mail programs complaining about the certificate.