[CentOS] multiple MX records

Mike Kercher mike at CamaroSS.net
Thu Nov 10 14:46:39 UTC 2005

centos-bounces at centos.org <> scribbled on Thursday, November 10, 2005 8:32

> Tom wrote on Fri, 11 Nov 2005 01:19:57 +1300:
>> I have 2 servers, 1 is DNS master and the other slave for a
> domain, if
>> I was to add a second MX record using the master servers IP for the
>> domain thats hosted on the slave would mail be held on the masters
>> mail queue if the slave was down?
> Forget about the dns master/slave, mentioning that just
> complicates it, mail queueing is independant of dns setup. If
> you add a second MX of lower priority mail will be sent to it
> if the MX of higher priority is not available. But you have
> to configure the backup MX accordingly so that it actually
> queues the mail and doesn't reject or try to deliver it locally.
> With sendmail you have to allow relaying for that domain but
> don't add it to the Local Domains list! Other mailers may
> need different actions.
> Be aware that lots of spam will be attracted by the backup MX!
> Kai

Agreed!  Backup MX's do attract more spam.  I'd highly recommend installing
MailScanner on BOTH MX's. 



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