I have had two clients recently mention that they could not send email to two different domains... it didn't bounce... it just disappeared...

When I look in the exim_mainlog, all messages to the domains in question wind up frozen after getting this error:

smtp transport process returned non-zero status 0x000e: terminated by signal 14

After talking with an admin at the one domain, I found that their first MX wasn't talking to me (no pings, no answer on telnet port 25)... but their second one was... I was dumbfounded why my server didn't re-try the message on the second MX if the first one failed, but I shrugged it off as a weird problem on their end. I faked out my /etc/hosts file to think their second MX was their first, and mail started flowing again.

Then I get the same error from another client trying to send to another domain, and I'm starting to think there's a problem here. It's too much to think that two different domains would have the same issue. I wondered if some new "improvement" in spam filtering was causing my email server to be ignored.

In both cases, the recipient domain's primary MX does not appear to be answering, which isn't my fault, I guess, but why isn't my server trying the second one? Isn't that the whole point of having more than one MX?

Any ideas? I ran /scripts/eximup --force and that didn't fix it.

More info on this... it appears to be getting more common, especially among college domains.

Email admins are purposefully advertising fake dead-end MXes as the primary MX! They think this will trick spammers.

Then they blame me because my mail server (the lastest version of Exim there is) is not passing over the fake MX and moving to the second.

In all my tests, this is what I'm finding... if I telnet on port 25 to the fake MX, I get "stuck"... it doesn't offer a prompt.. but it doesn't reject me... it holds on for about 5 minutes... which is about how long my exim seems to try before finally failing with the non-zero status signal 14 error...

So I'm thinking that exim is not moving along to the second MX because it doesn't see the first one as dead, but as slow... then it totally fails, rather than moving on.

Any way to tell exim to give up sooner and move on?

And are these email admins who are doing this accomplishing anything but breaking normal email delivery? Do they really thing spammers will not see through this in two seconds?