Exchange and application relaying


Running Exchange 2007 SP2. Multiple AD sites, each site has its own Hub, CAS and Mailbox server. Of all the sites, only HQ has Hubs that relay to the SMTP Gateways. Our mail domain is

We would like to bring in an application server for SiteA that can accept email from Exchange and send email to Exchange. Toplogy:

Outlook > Exchange > Application Server (users sending email to Application Server)

Application > Exchange > Outlook (Application Server sending email to users)

Only SiteA will have this application and only SiteA users will use this application.

Some questions:

1. In order for the Application server to send emails to Exchange, I assume we need to create some Receive Connectors. Would we create these on the Hub Transports in SiteA?

2. If we wanted to create the Receive Connectors first, but not have them being used for mail routing, can we set the cost to high (cost = 100 for example)?

3. In order for Exchange to send to the Application server, I assume we need to create Send Connectors. This is a global setting isn't it, unlike Receive Connectors which are per Hub Transport?

4. The Application Server *may* use the same domain name as Exchange, but have addresses like, How would we set this up seeing as was also being used by Exchange?

Any other points would be appreciated.
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NavdeepConnect With a Mentor Commented:

please find the answers below

1. You don't need to create a new receive connector. The one available on HT will be able to accept messages from app server. Make sure anonymous access is enabled on HT. Use the HT in a Site where your App Server resides.

2. You need multiple HT server and you need to set cost on Site link as site links will be used for mail routing. Also app server will  have hard coded HT server address rather than using AD site link cost to route messages

3. This depends upon how your app server receive messages, Is it binded to any mailbox user
    account. What domain address will you app server will be using. You need to explore custom send  connector options

4. Connected to the answer and counter question of 3.

PS: I have seen application sender relaying out of exchange and tied with exchange mailbox for the  purpose of receiving emails.

PostmasterConnect With a Mentor Commented:
If your application provides for a MAPI connection then it is just a mailbox like everyone else. By far the easiest way to set it up.
If you must go SMTP and POP then you will need to permit relaying for that server.
I prefer to keep applications off the hubs, and make them send in via the Edge server.
This can be done by allowing that IP to use the Send Connector.
neil4933Author Commented:

Why do you say we don't need Receive Connectors though? I thought that if Exchange was to receive email from a different system it would need a Recieve Connector on the associated Hub?
Because the default receive connector will be able to accePt emails from your app server
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