(Damn, left out a paragraph somehow)
And in fact, given that most link hiccups *are* transitory, the chances are *good*
that if our attempts at the first MX fail, the link will be back before we finish
running through the MX's - at which point we find ourselves talking to a spamtrap.
Which is why I prefer to set up a tarpit as my high-MX spamtrap, but not make it do anything permanent or even long-lasting. If you're a legitimate sender talking to my tarpit, it'll take you a while to discover that you can't make it through, and you should be able to successfully retransmit at a later time. If you're a spammer, it'll take you a while to discover you can't make it through, but then you probably won't try again.