Exchange 2010 Set-DistributionGroup Failed Error: The proxy address is already being used

I have an Exchange 2010 server on SBS server.  All users have email I added another domain 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 When I try to add I get this error message
The proxy address "" 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.
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Did you add this domain suffix as a new email address policy, in which case it may already exist for this user (sure you have checked but just checking), it may have faulted when it tried to create it.

The other time I have seen this is because the proxy address attribute had the address listed, now (from memory) I believe you can check this by looking at the distribution groups attributes in EMC or AD (I can't recall which) and checking if it is listed.  You can then remove it and see if it will auto populate properly or disable email address policies for this group and add it manually...
ajdratchAuthor Commented:
Yes, added suffix in address policy. Nothing is listed in attributes
Applies to Exchange online but should work for you also

Failing that use the following and do a search to track down the owner -

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ajdratchAuthor Commented:
The first link worked. I found it buried in a public folder
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