Re: Relaying mail FROM: a specific domain only

Planet X Mail wrote:
>
> I have a mail server that has problems with its IP address so I need
> to forward all mail coming from ( @mydomain.com ONLY no other domain
> ) to another mailserver we will call: 123.123.123.123
> [mail.externalserver.com]

So, basically this is just like a travelling salesman with a laptop, who
wants to send email using the mailserver from his company...

> What configs do I set in main.cf for the @mydomain.com POSTFIX What
> configs do I set in main.cf for the relay server?

If you don't know the IP address, and it isn't fixed: use SMTP Auth and
TLS to authenticate the sending host.

> ( @mydomain.com ONLY no other domain
> ) to another mailserver we will call: 123.123.123.123
> [mail.externalserver.com]

Additionaly, you can use smtpd_sender_login_maps so only mail with a
MAIL FROM in domain @mydomain.com will be accepted.
http://www.postfix.org/postconf.5.ht...der_login_maps


> On the @mydomain.com server set relayhost =
> [mail.externalserver.com] But, how do I ONLY relay mail from the
> domain @mydomain.com ??? and no other domains this mail server
> handles?

You should *not* relay mail based on what's in the MAIL FROM. Doing so
makes your server an open relay, because anyone can fake a MAIL FROM and
send email to anyone using your mailserver.

Greetings,
Hans van Kranenburg