There are multiple recipients matching the identity. please specify a unique value

Abdul Basith 136 Reputation points
2021-06-04T07:01:09.507+00:00

Hi,

I'm getting below error when adding a user to O365 Distribution List in Specified Senders.

There are multiple recipients matching the identity. please specify a unique value.

I Checked the mentioned user is not duplicated or not having a same display name..
Also not any contact list as a same display name
And also this issue is persisting from the O365 Exchange Admin Center and can add the user from O365 Classic Admin Center.

Exchange Server Management
Exchange Server Management
Exchange Server: A family of Microsoft client/server messaging and collaboration software.Management: The act or process of organizing, handling, directing or controlling something.
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  1. Vasil Michev 113.5K Reputation points MVP
    2021-06-04T07:57:42.233+00:00

    Using an alias/display name or any similar attribute is never a good idea. Best use unique-valued property such as the email address or UPN.

    2 people found this answer helpful.

  2. Ahmed Ehtesham Zaedi 11 Reputation points
    2023-06-20T12:21:50.45+00:00

    [UPDATE ON ROOT CAUSE n SOLUTION of user addition in demo distribution list (@test.com.bd) ISSUE : There are multiple recipients matching the identity "jhalak". Please specify a unique value.] In my test jhalak user has got multiple account (like @test.com.bd, @test1.com). Whenever we were adding UPN (@test.com.bd) it is changing it to "jhalak" after saving and closing out the dialog box. In my research, it came out that M365 is fetching an attribute named "Mail nickname" which can be found in azure AD and it is same for all the account like "@test.com.bd", "@test1.com". [SOLUTION:] If we change the "Mail nickname" from "jhalak" to "jhalak'" for "******@test.com.bd" we can successfully save and there is no save error. WOW!!! [NEED CALL FROM MICROSOFT:] Now we need a call from Microsoft what is the impact of changing the attribute name "Mail nickname".

    2 people found this answer helpful.

  3. Chris J Morley 0 Reputation points
    2024-01-15T22:33:41.7+00:00

    I had the same problem and worked around it by using a simple powershell command to achieve the desired configuration. It's a shame that the Mail Nickname is the field that's chosen, rather than a unique ID like the UPN. Try this: Set-Mailbox <Mailbox> -AcceptMessagesOnlyFrom <user>

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