MX Record Configuration

Gregory Hicks ghicks at
Tue Oct 31 17:09:19 UTC 2006

> To: bind-users at
> Subject: Re: MX Record Configuration
> Date: Tue, 31 Oct 2006 10:44:30 -0600 (CST)
> From: b19141 at (Barry Finkel)
> 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 
> >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 
> >and only if it is not possible will sending MTAs fail over to your 
> >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.

Spammers deliver mail to the higher numbered MX hosts deliberately 
because they figure that the anti-sapm measures on the backup mail 
server are not as good as on the primary mail servers.

> ----------------------------------------------------------------------
> Barry S. Finkel
> Computing and Information Systems Division
> Argonne National Laboratory          Phone:    +1 (630) 252-7277
> 9700 South Cass Avenue               Facsimile:+1 (630) 252-4601
> Building 222, Room D209              Internet: BSFinkel at
> Argonne, IL   60439-4828             IBMMAIL:  I1004994

Gregory Hicks                           | Principal Systems Engineer
Cadence Design Systems                  | Direct:   408.576.3609
555 River Oaks Pkwy M/S 9B1
San Jose, CA 95134

I am perfectly capable of learning from my mistakes.  I will surely
learn a great deal today.

"A democracy is a sheep and two wolves deciding on what to have for
lunch.  Freedom is a well armed sheep contesting the results of the
decision." - Benjamin Franklin

"The best we can hope for concerning the people at large is that they
be properly armed." --Alexander Hamilton

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