The plan was to eliminate SquirrelMail with the release of version 78 of the cPanel software leaving only Horde and Roundcube. Well, version 78 reached its stable release and we updated servers at the end of February. "Poof!" SquirrelMail was gone.
Not a big deal you say. There are two other webmail clients. But some users also had built up a pretty extensive address book and, well, that was gone too. Fortunately. I found a tutorial on the cPanel Forums to export the SquirrelMail Address Book data (yes, it still exists) and import it in to either of the other webmail clients.
After a bit of experimentation, we were able to make this work for a few clients who contacted us. So, if you have found your SquirrelMail address book disappeared. Let us know. We can help.