Judging form this thread:
http://lists.ccil.org/pipermail/fetc...er/005395.html
It does support IMAP
Can you telnet to port 143 on the server?
And this search:
http://www.google.com/search?q=Lotus...ient=firefox-a
Tells me that you probably arn't all that safe, although I would venture to say, based upon experience, that the likely hood of an attack is low.