[nflug] Postfix Store and Forward

[Eric Toczek]

Robert Wolfe wrote:
> Hi all!
>
> I am currently running Postfix on my mail servers and I have a client
> that would like to use me an an MX since his ISP does not allow
> incoming connections on port 25 and he has a connection to my VPN. 
> Basically, I would like Postfix to accept emails destined for his
> domain and then transfer those emails, over the VPN link with his
> system, to his machine.  However, I have no clue as to where to start
> going about doing this.  Has anyone set up Postfix in a similar manner
> to do this very thing and if so, how?

in main.cf:

add the domain name for their domain to the end of "relay_domains"
 
add "check_relay_domains" to smtpd_recipient_restrictions

then finally add:
transport_maps = hash:/etc/postfix/transport

so then create a transport map at that above location, structured like so:
domain.tld smtp:their.ip.or.hostname

ex:

example.com smtp:192.168.0.15

-----

That will allow your smtp server to accept mail for their domain, and
forward that mail onto the ip or hostname you supply for delivery. The
one gottcha is that you're not checking for valid accounts, so it could
create backscatter spam if their mta decides to send out bounce
messages. If you could query their user database to check for valid
accounts first that would solve the backscatter.



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