Quoting Marc Perkel:
> I was just wondering if there were known MTAs that don't try all MX
> records but only the lowest? Is this something that's common?
I guess by "lowest", you mean the lowest preference number, i.e. the
highest priority.
qmail ist known for strange behaviour. AFAIR, it does only fall back to
lower priority MXs after a connection failure, but not if the
connection was established and a smtp error response was given.
I'm not astonished. qmail has so many flaws that somebody even bothered
to set up a web page documenting it... ah, here it is:
http://home.pages.de/~mandree/qmail-bugs.html
quote: "... that qmail would never try any other MX than the first it
connects to, even if that MX does not reply with a 220 greeting. When
the server replies with e. g. a 554 greeting, qmail disconnects and
later retries the same server again, ignoring the fact that 554 is a
permanent error."
