Multiple domains, multiple exchange servers SAME subnet

Posted on 2010-01-09
Medium Priority
Last Modified: 2012-05-08
I have two domains with their own exchange servers with real world IP addresses mapped inside to a single ASA.  One domain has an inside IP of x.x.5.2 and the other x.x.5.26
Mail will not travel between these two mail servers because, I think, the exchange servers are set to resolve from external DNS's.  Sooo, when you send mail, it bounces because the external IPs are already mapped inside.  It can't go outside and back inside to deliver mail.  Tracert fails on first hop.  If this is not something I can resolve via exchange 2003 and exchange 2007 and I should repost to a DNS area, please advise and I apologize.
Question by:davebird
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
LVL 71

Expert Comment

by:Chris Dent
ID: 26275555

You have a few options open to you here:

1. Fix the Firewall Configuration, will need NAT loopback. I can't give you instructions on that.
2. Create SMTP Connectors from one mail system to the other. Bypasses MX Record lookup, direct delivery for specific address spaces between the two systems.
3. Create an internal only MX record for each mail domain.

The second would seem like the best choice from my point of view, the third is entirely possible but carries a higher administrative cost.

LVL 49

Expert Comment

ID: 26276452
Hi I would definitely do what Chris proposed in point 2.

However having the exchange servers using external DNS is not a good idea since they should be able to communicate with the DNS server hosting their active directory zone.

LVL 32

Expert Comment

ID: 26276501
These are seperate Exchange Orzganizations? So I am assuming seperate AD Firests too :) Am I right here.....
Create seperate Send Connector on each Exchange Orgs pointing to each Exhange server for smart host for delivery. Same as Chris!
Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!


Author Comment

ID: 26306892
My apologies.  I am "learning" more about send connectors as they seem to be associated with smart hosts to handle ALL mail instead of internal routing.  Most of the threads I've read from MS and from third parties are saying the same thing. A Send connector, whether it's a routing or all, still thinks mail is being sent to a device that will handle all routing.  I simply want mail from two individual domains and two separate/individual exchange servers inside the same subnet but valid External IP addresses through a single cisco ASA to allow traffic to pass properly.  All comments are valuable, I'm just not educated enough on how to create an internal connector between two servers as of yet.  Please don't show this issue as closed or abandoned.  
LVL 71

Accepted Solution

Chris Dent earned 1000 total points
ID: 26306974
Hi Daver,

The Address Space tab on the SMTP Connector properties allows you to specify a set of, or a single domain name. That means you can create a number of different SMTP connectors, each handling mail for different outbound domains.

It works well in this scenario because you can have one SMTP Connector to deal with mail to @domain2.com (which forwards to the second Exchange server), and another to handle everything else (using * as the address space).

Pictures might help... look at this article:


Head down to the point he has the Address Space tab open. You'll see he has contoso.com in there, that means the connector will only deal with mail sent to that domain from the local Exchange server.

If you want to explore the ASA then the request needs to be in a different topic area. I'll happily link it up and send out alerts if you wish?


Author Closing Comment

ID: 31675061
Thank you for everyones qualified input and quick responses!

Featured Post

Office 365 Training for IT Pros

Learn how to provision tenants, synchronize on-premise Active Directory, implement Single Sign-On, customize Office deployment, and protect your organization with eDiscovery and DLP policies.  Only from Platform Scholar.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

MS Outlook is a world-class email client application that is mainly used for e-communication globally.  In this article, we will discuss the basic idea about MS Outlook, its advanced features, and types of MS Outlook File formats.
If you troubleshoot Outlook for clients, you may want to know a bit more about the OST file before doing your next job. IMAP can cause a lot of drama if removed in the accounts without backing up.
In this video we show how to create an Address List in Exchange 2013. We show this process by using the Exchange Admin Center. Log into Exchange Admin Center.: First we need to log into the Exchange Admin Center. Navigate to the Organization >> Ad…
In this video we show how to create an Accepted Domain in Exchange 2013. We show this process by using the Exchange Admin Center. Log into Exchange Admin Center.: First we need to log into the Exchange Admin Center. Navigate to the Mail Flow >> Ac…
Suggested Courses

762 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question