Re: [exim] Is a secondary MX worth the effort?

>> > One of the things I've considered for #2 is having a secondary MX
>> > which is configured to give back a 4xx for everything.
>>
>
> We have this kind of setup for about a year now and never experienced
> any problems. As many spam-senders tend to use the backup-MX for spam
> delivery, our 4xx-MTA catches a lot of spam. If you "tail -f" the
> logs, you only see suspicious hosts connecting. It also decreased the
> load on the primary servers.
>

I understand the value in this setup as a SPAM honeypot, but the
question I suppose I still need answered: Is there [technically] any
availability benefit provided by a second MX of this nature versus the
self-retry feature most mail servers utilize? Won't a 4xx message
result in the same behavior as if I can't connect to a primary? With
both messages getting deferred for retry?

And if that is indeed the case, I go back to my original question: "Is
a secondary MX worth the effort?"