Active Directory domains and Exchange e-mail

I needed to set up an Active Directory domain and route e-mail to the users using Microsoft Exchange 2003.

Now, Microsoft suggests that you name your (small) domain with the .local suffix, such as "mycompany.local".

Obviously, this is not a valid e-mail domain name, and say you have registered mycompany.com as your e-mail domain.

My initial thought was that it would be enough to add the e-mail addresses of the "mycompany.com" format to the Active Directory User's And Computers (for each user that is), but this did not work.

Instead, you need to explicitly tell Exchange to accept mail for the domain mycompany.com. To do this, edit the default recipient policy, as outlined in Microsoft's Knowledge Base article 268838.

Note that whenever Exchange asks for an SMTP domain name, you need to include the @ sign, that is, "mycompany.com" is not a valid input, but "@mycompany.com" is.