For a list with open subscriptions, I think that deleting addresses
which have bounced is actually friendlier to users than setting them to
nomail. If a user stops getting mail from a list, one natural reaction
is to send another subscription request. If the address has been deleted,
then the user will be subscribed again. If the address has been set to
nomail, then the SUB command will be processed as a name-change request
and the user will still be set to nomail. I don't see any advantage to
NOMAIL if subscription is open and the logs are public.
 
David