> Clever trick. Do legitimate MTAs try to send to the second > highest MXer if the primary is down? If so a fake third MX > (even to a completely unused IP?) may have little downside. > > I.e. > > @ IN MX 5 realprimary.domain.com > @ IN MX 10 realbackup.domain.com > @ IN MX 20 fakebackup.domain.com > > Jeff C.
AFAIK mailservers first try the highest prio, then the second highest etcetera. I once had a situation where both the primary and the secondary were down, but still mail to us didn't bounce, old mails just started streaming in when the servers came up. Somehow the mail-protocol is quite robust, I'm not worried about using a 'fake' third MX. Menno
