Has anyone here (been crazy enough) to attempt reading from a shared mailbox using javamail?

To be fair, this doesn't seem like the sort of area that java game devs specialize in.  Might try a different forum?  I've got more of an enterprisey background, but I don't use JavaMail directly (I use higher level wrappers).  But anyway, as long as your IMAP server has no problems with multiple sessions reading a mailbox, JavaMail won't either.  It will lock an individual message to prevent concurrent flag modification (at least that's what the javadoc tells me) but the mailbox itself seems to be fair game.