This is a two parter.
Q1: How do I add external email addresses to Exchange distribution list?
Q2: How do I forward someones email to and external email address?
A: AD Contact Objects.
First let’s setup a distribution list with internal email addresses and then add and external email address.
Creating a Distribution List
1. In AD Users and Computers browse to your group container.
2. Right click on the container and choose New > Group
3. For Group name enter the name of the distribution list, choose the scope (Global by default) and choose the type: Distribution, and then click next.
4. Check the box “Create an Exchange e-mail address” and click Next
5. Click Finish
6. Right Click on your new group and choose properties
7. Go to the members tab and click Add
8. Add all of the internal accounts that you want on this distribution list and click OK
Adding an External Email Address to a Distribution List
9. Create a new AD container named Contacts if you don’t have one already.
10. Right Click on the Contacts container and choose New > Contact
11. Fill in the First Name, Last Name, Full Name, and the Display Name and click Next
12. Check the box “Create and Exchange email address”
13. Click the Modify button.
14. Choose SMTP Address and click OK
15. Enter the External Email address and click OK
16. Click Next and then Click Finish
17. Go back to your distribution list, right click and choose properties.
18. Go back to the members tab and add the new contact you created (you may have to click “Object Types” and include Contacts)
19. Your Distribution List is ready to be used.
Forward Email to an External Account
1. Create a new Contact in your Contact AD container.
2. Fill in the First Name, Last Name, Full Name and Display Name. I like to make the Full Name and Display Name contain something that indicates this Contact is used for forwarding, ex: Jess Watts Forward, Click Next
3. Check the box “Create an Exchange email address”
4. Click Modify
5. Choose SMTP address and click OK
6. Enter the external email address and click OK
7. Click Next and then click Finish
8. Now locate the AD user who’s email you want to forward, right click on their account and choose properties.
9. Click on the Exchange General tab
10. Click on the Delivery Options button
11. Under Forwarding address choose Forward to: and then click Modify
12. Select the Forwarding contact you created earlier.
13. Optionally, check the box below that says “Deliver messages to both forwarding address and mailbox” if you want a copy to be maintained on the Exchange server.
14. Click OK on the Delivery Options dialog and the User’s Properties dialog.
15. Email will now be forwarded to the external account.