Re: Email routing like MX functionality

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Email routing like MX functionality
\ Robert Fitzpatrick (15 May 2007)
. \ Noel Jones (15 May 2007)
. . \ Robert Fitzpatrick (15 May 2007)
. . . \ Noel Jones (15 May 2007)

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Subject:	Re: Email routing like MX functionality
Group:	Postfix-users
From:	Noel Jones
Date:	15 May 2007

At 12:50 PM 5/15/2007, Robert Fitzpatrick wrote:
>On Tue, 2007-05-15 at 11:32 -0500, Noel Jones wrote:
> > At 11:08 AM 5/15/2007, Robert Fitzpatrick wrote:
> > >I was wondering if routing similar to having multiple MX records is
> > >possible with our Postfix 2.3.5 gateway. We have several MX records
> > >setup to send mail for a domain to our gateway. Can the gateway be told
> > >to fail over to another IP is one is not responding? If so, can someone
> > >point me to the appropriate info? Thanks in advance.
> >
> > The normal way to do this is with private MX records. A hostname
> > something like internal.gateway.invalid listing the internal IPs and
> > their priority, and a transport map pointing the internal domain to
> > the custom MX record.
> >
> > A alternative is to use smtp_fallback_relay on the master.cf
> > transport you use for delivering internal mail.
> > http://www.postfix.org/postconf.5.html#smtp_fallback_relay
> >
> > It's not entirely clear what you are trying to accomplish. Specifics
> > of that might get you more specific answers.
> >
>
>Thanks, sorry for the limited info. I want to see if this can be done on
>a domain name basis. I have a customer that wants to put in two
>firewalls, one as a backup. We use our relay_transport mapping to send
>his filtered mail to their existing firewall. Can it be setup to try
>another if the first is not responding for his domain only?

Yes. I think the easy way is to use private MX record using either
".invalid" or ".local" as the tld, something like
gateway.customer.invalid and point your transport map at that domain.
# transport map entry
customer.tld relay:gateway.customer.invalid
note: no "[ ]" brackets to allow MX lookups.

Or you can add a copy of the "smtp unix ..." transport that is
specific for that customer, and point your transport map at that entry.
# transport map entry
customer.tld customer-relay:[gateway1.cust.tld]
note: use "[ ]" brackets to disable MX lookups.

# master.cf
customer-relay unix - - n - 2 smtp
-o smtp_fallback_relay=[gateway2.cust.tld]

Both methods work equally well, use whichever is more maintainable for you.

--
Noel Jones