[exim] Yet Another ANTI-SPAM Trick

Again - noticing that I get a lot of spam atempts on the HIGHEST MX
record - I sert up a FAKE IP address for my highest MX.

I now have 3 MX records:

smtp1.ctyme.com - mail server
smtp2.ctyme.com - real backup server
smtp3.ctyme.com - fake backup server

The 3rd server - which is really just a different IP address on my main
server always returns DEFER creating a temporary error. Many spammers
never retry so the spam goes away. Is a very inexpensive spam deterrent
and have very low cost in computer resources.

defer    log_message = Spammer Connected to FAKE highest MX record
        condition = ${if 
match{$interface_address}{209.237.228.13}{true}{false}}
        delay = 3m

The delay gives me the illusion I'm punishing them.

There's no email losses because real email will eventually retry the
mail real server on the lowest MX record.