Joel> My understanding is that even with nfs locking having multiple Joel> systems do delivery is not safe.

Probably, though having one delivery system and multiple POP/IMAP system might be nearly as bad. It depends.

Joel> Could you live with a single (+ backup) delivery system? Having Joel> several MXs of different preferences should be ok as I would Joel> expect only one to actually be delivering mail at any time.

Probably. We'll have to test performance for this setup. -- Alan