I have an Exchange 2010 server on SBS server. All users have email @domain1.com. I added another domain @domain2.com. I updated all the users so they have email addresses at both both domains. This worked for all users and all but one distribution group.
The distribution group is firstname.lastname@example.org. When I try to add email@example.com I get this error message
The proxy address "smtp:Attorneys@domain2.com" is already being used by "domain.local/Microsoft Exchange System objects/Attorneys 54302259". Please choose another proxy address.
I have search Exchange and AD. I cannot find "Attorneys 54302259" anywhere. The only other reference to Attorneys in AD is a public folder with that name. That public folder does not have an email address associated with it.