MX Record Configuration

Kevin Darcy kcd at
Wed Nov 1 00:37:00 UTC 2006

Barry Finkel wrote:
> Kevin Darcy replied to a posting:
>> There's nothing magical about the first label of the name, in SMTP 
>> terms. The only thing that really matters in terms of SMTP failover is 
>> the preference value. If your box -- whatever it's called -- has a 
>> preference of 5 and your ISP's box -- whatever it's called -- has a 
>> preference of 10, then mail will be delivered to your box, if possible, 
>> and only if it is not possible will sending MTAs fail over to your ISP's 
>> server.
> When I last looked at spam statistics on our backup mail relay box,
> I found that 25% of the mail to that box was legitimate mail, and
> 75% was spam.  I know that our primary mail relay box was not
> unavailable 25% of the time, so there are mailers on the Internet
> that do not follow the rules in the MX RFC.  I did not have time to
> look at some of the mail to try to determine what mail software
> delivered the mail to the higher preference MX host
It's true that some spammers deliberately subvert the SMTP algorithm in 
an attempt to find a "soft" mail gateway that doesn't apply the same 
anti-spam rigor to incoming mail.

But I'm not aware of any spammer giving any special meaning to mail 
gateway names with a first label of "mail" or "post" or whatever, which 
was what I was responding to above.

                  - Kevin

More information about the bind-users mailing list