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Configuring Exchange to host multiple e-mail domains

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Configuring Exchange to host multiple e-mail domains


It's fairly common for most organizations to have multiple Internet domain names.  In some of those cases those Internet domain names need to be used for incoming SMTP e-mail.  Exchange provides support to accept mail from multiple domain names and also set the SMTP e-mail address on users based on recipient policies.  In this article I will cover configuring Exchange to accept e-mail for multiple SMTP domains and creating recipient policies to give users the correct e-mail addresses.

The first step in configuring Exchange to accept e-mail for any domain is to register the domain at one of the many registrars.  During the registration process you need to list the DNS servers that will be servicing the new domain.  I suggest using an external provider to host your external DNS entries for Internet queries.  I also suggest using the external provider as a secondary\backup DNS provider and keep a local DNS server as your primary\master DNS server.  This will allow you to easily make changes to your DNS records and these changes will then be replicated to the external provider's DNS servers.  This will allow you to lock down your firewall and DNS server to only allow zone transfers and queries from the external provider's IP addresses.  Once the domain has been registered and DNS is setup you will then need to add MX record(s) for the Exchange servers that will be handling incoming e-mail.

Configuring Exchange to accept e-mail for a new domain

Once the domain and DNS are configured, Exchange needs to be configured\told to accept e-mails from the domain. To do this, follow the steps below:

1.      Open up Exchange System Manager (ESM)

2.      Navigate to <Org>\Recipients\Recipient Policies

3.      Double click on the "Default Policy"

  • In a fresh Exchange single admin group environment you will only have the "Default Policy" listed; in my environment I have multiple recipient policies.

  • If you upgraded from Exchange 5.5, a policy might exist for legacy Exchange 5.5 site.


4.      Click on the "E-Mail Address (Policy)" tab

  • In a fresh environment only two entries will normally be listed, one for SMTP and another for X400.


5.      Click New?

6.      Select "SMTP Address" and click OK

7.      Enter in the new domain you want Exchange to accept mail for, it must start with an "@"

8.      Click OK

9.      If you want all users to get this new e-mail domain name as an additional SMTP address click the check-box in front of it

  • Users will be given an address of <mailbox alias>@<domain> if you check the box.  In most cases you will want to control who gets certain e-mail addresses.  This will be covered next.

Configuring Exchange to host multiple e-mail domains

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Copyright Stephen Bryant 2008