FAQ: Why can I not send to Internet users that have the same domain as my Exchange Server?


When you assign a domain to Exchange Server it assumes all email addresses with that domain are local.

Here is an example:

The company Acme has the Internet domain acme.com. Acme has Internet mailboxes at their ISP receiving mail for joe@acme.com and alice@acme.com. Alice is a user on Exchange Server but Joe is not. He pulls his messages down using his own email client from a remote location.

Now, Alice needs to be able to send mail to Joe but since her Exchange Server is configured as acme.com she cannot send mail out to joe@acme.com.

Solution

Assign a different domain to your Exchange Server (eg. acme.local.com).

Assign all your users on Exchange Server a second SMTP address with the domain part being acme.local.com. Each user should still have an SMTP default address with the domain part being acme.com, so when they send messages their return address is still acme.com.

Now, Alice can send to joe@acme.com because Exchange Server's local domain is acme.local.com not acme.com.

To receive messages you need to configure eXchange WALL to send the messages it pulls down to acme.local.com.

If Alice was receiving her Internet mail at an account assigned just to her (single user account) then in eXchange WALL change this account to send its messages to alice@acme.local.com.

If Alice was receiving her Internet mail at an account assigned to more than one person (multiple user account) then this account still needs to look for acme.com addresses. Instead, setup a rule in the eXchange WALL Rule section that for any messages downloaded from this account map the domain from acme.com to acme.local.com