Yes - I've thought about this a bit.
But the thing to remember in this particular case is that outgoing mailings
are handled by ezmlm.  Mailhandler sends a single email to the list and the
    

I would be more interested in the incoming messages (from the list to
the forum). My experiments trying to make this work (using either POP3
or IMPA to access a mailbox) revealed that for low traffic it works
fine but when the traffic increases the imap_open() process can't keep
up.
hmm....  This sounds like a Mailhandler/PHP issue - I'm not sure what could be done here.  Is it that imap_open() doesn't work right?
I'd be very interested in testing your new code on my testbed if
you've resolved the above issue.
Not sure how I would do that.  We'll be releasing the code soon - if you want it before then mail me and I'll send it.  Right now it assumes ezmlm.

Dan