Seamonkey (formerly known as Mozilla/Netscape Suite) is added to EPEL6 .
Try it at updates-testing for now.
It is the latest stable version 2.12.1, based on the shared sources with
firefox-15/thunderbird-15.
The current RHEL6's firefox/thunderbird have version of 10.0.x (ESR -
extended support release), hence seamonkey can provide more recent
things etc.
Regards,
Dmitry Butskoy
http://www.fedoraproject.org/wiki/DmitryButskoy