[TriLUG] to whom do I send SMTP?

[Jon Carnes]

> --- "Neil L. Roeth" <neil at occamsrazor.net> wrote:
> > On Sep 30, Jon Carnes (jonc at nc.rr.com) wrote:
> >  > By default Sendmail does a DNS based MX lookup to
> > find the proper
> >  > mailserver, and then attempts a direct
> > connection. If that fails, it
> >  > moves on to the secondary. Most small/medium
> > businesses use their ISP's
> >  > mailservers as a secondary (or tertiary).
> > 
> > How do you configure sendmail to use a secondary
> > server?

You don't do this in Sendmail. You do this in DNS.

In DNS you setup a secondary MX record:

  Domain    IN   MX   10 primary.mail.server.com
            IN   MX   20 secondary.mail.server.com

On the Secondary.mail.server.com you only have to add the Domain as an
allowed relay.  In the file /etc/mail/access:
  Domain.name.com     allow

===

Sites looking to drop off mail to your domain will attempt to contact
"primary.mail.server.com".  Failing that, they will contact
"secondary.mail.server.com" and drop off the mail for "Domain.name.com".

The Secondary server will then try to relay the mail on to the Primary
server several times.

Jon