postfix question

Ted Mittelstaedt tedm at
Wed Apr 25 10:48:31 UTC 2007


UNIXes and suchlike use a single IP address route table.

Your machine isn't trying to establish a connection to:
username at

It is trying to establish a connection to IP address

Machines don't speak domainese.  They translate
the human-friendly stuff like domain names and such into
IP addresses.

Once the system resolves the recipient e-mail address
into a destination IP address, the choice of interface that
it goes out on is entirely controlled by the route table.
And due to the single route table in the system, that
is going to be the interface that reaches your default gateway.

Even if this box was a router, like a Cisco that supports
route maps that allow you to bypass the single route table,
since the mail is originating from the system, it would always
follow the same map anyway.

You need 2 mailservers to do what you want.


> -----Original Message-----
> From: owner-freebsd-questions at
> [mailto:owner-freebsd-questions at]On Behalf Of Gerard
> Sent: Wednesday, April 25, 2007 3:38 AM
> To: User Questions
> Subject: Re: postfix question
> On Wednesday April 25, 2007 at 03:27:48 (AM) n j wrote:
> > Hello,
> > 
> > does anybody know is it possible with Postfix to "route" e-mail based
> > on either the inet interface message came from or the sender of a
> > message? I'm using Postfix v.2.3.8 on a multihomed machine and have
> > two smtpd's defined in What I would like is that mail
> > submitted through smtpd that is listening on A.B.C.D goes out through
> > the smtp client that binds to A.B.C.D and the rest of the mail go
> > through the other smtp client. The problem as I see it is that, once
> > messages arrive in the queue, it becomes irrelevant where they came
> > from and the only "routing" that is available is recipient-based.
> > 
> > Thanks for any suggestions!
> You would probably get better assistance if you asked this question on
> the Postfix forum.
> -- 
> Gerard
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