On Fri, 2005-12-02 at 19:34 +0100, Aram Galestian wrote: > you should not block Null senders case that used for DSN .. and you if you
> block NULL senders then you do not will recive any dsn message.
> But you can block Null senders more that have more then one recipeint,
in most cases this will be fine, but there is a legitimate possibility
for a bounce to have more than one recipient.
system A: your system, accounts alice and bob.
system B: a mailing list host running Sendmail
system C: the host with a faulty address
if both Alice and Bob are administrators for the mailing list, they may
receive a bounce from the mailing list host for the faulty address at C.
since it's the same bounce, system B is allowed to send the two copies
of the bounce in the same transaction to system A.
in practice, this won't happen often these days, since most people are
using mailing list software rather than old fashioned alias files.
--
Kjetil T.
