[Mimedefang] Many many MX records

Gary Funck gary at intrepid.com
Tue Jan 13 23:50:21 EST 2004



> From: David F. Skoll
> Sent: Tuesday, January 13, 2004 2:03 PM
> To: MIMEDefang,
> Subject: Re: [Mimedefang] Many many MX records
>
>
> On Tue, 13 Jan 2004 WBrown at e1b.org wrote:
>
> > This led me to wonder  what would happen if I registered a bunch of high
> > valued MX records, ie:
>
> > Domain.com      IN MX 10        mailfilter.domain.com
>
> > Domain.com      IN MX 100       bogusaddress.domain.com
> >                 .
> >                 .
> > Domain.com      IN MX 200       bogusaddress.domain.com
>
> I wouldn't recommend doing this.  DNS uses UDP, and it's inadvisable to
> have so many MX records that they won't fit in one decent-sized
> UDP packet.
> It will cause a lot of load on your DNS server, and I bet will trigger
> weird bugs in a lot of resolver libraries out there.
>
> It would also hurt legitimate senders, especially ones that aren't smart
> enough to discard duplicate MX records.

How about
    Domain.com      IN MX 100       spamtrap.domain.com

And set up spamtrap as a real or virtual server, which might safely assume
that mail directed at is either spam, or mail from broken MTA that doesn't
deserve the privilege of sending mail to domain.com.




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