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Re: [SLUG] Secondary MX record - To have or not

This one time, at band camp, David Fitch wrote:
>one point that no one else has mentioned and is a big problem
>with having a secondary mx is spam.  I am my own primary mx
>and block various domains and IPs cos of spam.  Trouble is an
>increasing amount of spamming software if it gets a reject from
>the primary mx goes on and tries all the other mx's.  So unless
>you can control the blocklists at your secondary (and other) mx
>sites (which usually you can't if it's your ISP) you will still
>get all the spam and might as well not bother blocking anything.

Empirical evidence shows that spamming software will use the first and the
last MXes, by precedence.  So, you do the most amount of spam blocking on
your primary, as per usual, and have 4 or five secondaries.  The last of
them you'll never end up using, (the chances of 5 MXes going offline are
pretty slim, right?) so you just drop all mail that goes to the last MX :-)

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