An updated squirrelmail has been released for CentOS-3 that removes a trademark problem.
https://bugzilla.caosity.org/show_bug.cgi?id=682
Updated file is :-
squirrelmail-1.4.3-0.e3.1.centos.1.noarch.rpm
in updates/i386/RPMS/
These are available at http://mirror.centos.org/3.3/ and should be on all mirrors within a few hours.
To update to the latest version 'yum update squirrelmail' should be sufficient.
Lance