>From Eric Allman's interview on sendmail.net:
>Are there features in sendmail that people should be aware of but
>aren't?
>
>Oh, there are probably dozens of them. One that comes to mind, a very
>simple one, is the fallback MX option, which lets you redirect mail
>that has failed the first time to another location. It essentially
>acts as a lowest possible priority MX record for all hosts. For
>example, if you've got a mail system that's got a lot of traffic
>going through it, you have another machine that you dedicate to the
>slow mail, the stuff that didn't go through the first time, where
>presumably you're less concerned about how quickly it goes because
>the other end's being slow. So you set your initial connection
>timeout to something low - five seconds, ten seconds, whatever's
>right for your site - and you set the fallback MX on your main site
>to this fallback host. That way the mail that's going to go through
>quickly just goes fsssssssst right through your main server, while
>the stuff that's going to be slow (because the other end is either
>slow to connect or down) goes off to this other machine and doesn't
>clog up the main machine. It turns out to be just an amazing win. And
>these days the price of a PC box running FreeBSD or Linux is close
>enough to zero that it might as well be zero, so it's not really a
>problem to do it
Any thoughts about how to do this with qmail? Or reasons why it's a
bad idea?
-Dave
