I have attempted to create an external contact in our Exchange 2013 environment for an something.something.ctr@us.af.mil and continue to receive the following error:
The address 'something.something.ctr@us.af.mil ' is invalid: "something.something.ctr@us.af.mil " isn't a valid SMTP address. The domain name can't contain spaces and it has to have a prefix and a suffix, such as example.com.
Any clues how to fix this?