Arnt Gulbrandsen wrote:
I'd try to skirt the issue
Dunno, noting that a backup MX is in a situation exactly at the
time when it's really needed makes sense. But maybe an example
in an appendix isn't the best place for this point (?)
"foo.com, having received the message, verifies delivery to
jones(_at_)xyz(_dot_)com is permissible and possible. foo.com now does
a DNS lookup on xyz.com."
Actually it should verify jones(_at_)xyz at the time when it decides
to accept the mail, but at this time xyz is down, and so that's
not possible. The verification business after it has accepted
the mail is pointless, it's too late, foo.com can only pray
that xyz.com eats its spam.
Frank