[Mailman-Users] RFCs ... (mailman+mailer) ...

[Dan Mick]

> (a)  does  mailman make a copy of the message to each of the
> recipients  (as  majordomo does) or does it work in the form
> of a (listserv) job such as

> i.e.  sending the message with distribution list to a server
> and   "exploding"  the  contents  due to some routing tables
> arrangement, saving much bandwidth and cpu time, etc. ...

yes, although I can't believe Majordomo doesn't do that as well.
Mailman will send mail to N users using M SMTP transactions
(or invocations of sendmail if you have it so configured),
where M = N / (some constant).