So we setup a site to site vpn tunnel with another company. We then proceeded to setup a DNS zone on each others dns servers and entered in each others Mail server name and IP, MX record and WWW record. This allowed us to send emails to each others mail servers through the site to site vpn.

Now recently the other company started using MX Logic to scan all outbound and incoming mail. So all outbound email is directed to MX Logic.

However we still want email between us to travel across the the Site to Site VPN tunnel. How can we specify that to happen for just one domain not to be directed to MX Logic?

Stump on both ends and looking for help.

  • What is the MTA in use? – Ignacio Vazquez-Abrams Apr 6 '10 at 16:30
  • I am certain they are using SMTP, however I do not have access to the other companies servers. They are not sure how to set this up to work, and I am trying to investigate and find a solution for it. – jherlitz Apr 6 '10 at 17:26
  • telnet to the smtp server on port 25 and see if the banner tells you anything – Zypher Sep 19 '10 at 0:53

sendmail: Add an entry in mailertable to specify an smtp server for the appropriate domain.


With postfix, you can use a transport map to accomplish this.

The basic plan would be to create a file named transport in your /etc/postfix directory, and fill it with something like this:

otherguysdomain.com smtp:mailserver.otherguysdomain.com 

Add this to your /etc/postfix.main.conf:

transport_maps = hash:/etc/postfix/transport

Compile the map like so:

postmap /etc/postfix/transport

The reload postfix:

postfix reload

You can learn a little more about transport here.

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