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Relay emails to different external hosts

Created: 24 Jun 2013 | 3 comments
john.ts's picture


I recently came up with a demand to relay emails to external hosts. To become clearer, here's what i need.

We have 3 sites A(Primary site),B,C. Lets assume that there is no site-to-site vpn connection.

We have one domain,

What we want to do is, when an email arrives to the messaging gateway at site A, to check where the recipient is located (site B,C) and forward it there, instead of delivering it to site A.


Additional info.

For the time being all 3 sites have a vpn connection. All 3 have Exchange 2010 which is configured to distribite the email to each site (but that happens after it is delivered to site A, the exchange on site A takes care of the distribution). We are having problems with the vpn site-to-site connection so we are trying to find an other way around it. All users are under the (no etc exists, and it is something we would like to avoid)

Thank you

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BenDC's picture

You can use Protocols -> domains to direct specific addresses to specific mail servers.

You may also be able to use the address resolution feature, howerver it will likely also encounter the issues you are having with the site to site vpn as well as likely require some reconfiguration of your internal LDAP/Exchange servers so that they can return what server the mail should goto to the Messaging gateway as it sounds currently all would still likely be directed to site A.

john.ts's picture

Thanks for the suggestions Ben.

Luigi81's picture

Hello John,

You can solve your problem with a content filtering rule. You only need a list of the recipients of site B and C and the IP of your servers in site B and C. Just follow this steps:

  1. With your list of recipients of site B and C, create a dictionary for each site. To do this go to tab Content > Resources > Dictionaries. You can export your lists in txt format.
  2. Create a content filtering rule.
  3. The condition for the content filtering is:
  • Select radius button --> Text in the specific part of the message header:
  • "Contains"
  • “Email address”
  • “Envelope recipient”
  • “Dictionary for site B”
  1. The action for the rule will be:
  • Route the message:
  • Host: “IP_address_server_site_B”
  • Port: “XXXX”

5.     Policy groups, select all the groups you have in your environment.

6.     Repeat all steps above for site C.

This should work for your environment Ben.