Slightly OT - MX RR Santity Check requested...

Wael Shahin wael.shahin at
Thu Mar 29 10:44:41 UTC 2007

> Assume that we block the pref 5 MX host (which we do).  Shouldn't sending
> hosts use the pref 10 MX RR?
Maybe am wrong, but some mail servers stop trying when they actually get an 
answer. meaning if the external mail server was able to connect to port 25 
and got an SMTP permanent errors like your host is blacklisted. the error is 
returned to the client without trying other mail servers in the MX zone

> ... Kev

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