Six.

LogicMail for BlackBerry
http://www.logicprobe.org/proj/logicmail

"LogicMail is a J2ME E-Mail client supporting IMAP and POP, and designed to run on RIM BlackBerry handheld devices. Its goal is to provide an alternative to the service-oriented "push" E-Mail system that the device normally provides, so we can also use our conventional E-Mail services."

My Blackberry is personal, I use LogicMail to on-demand check into my work email over IMAP/SSL rather than have it all pushed to my device. Been using if for some time, it works quite well.