How to fix "There are multiple recipients matching the identity "or". Please specify a unique value" error

Mihai Nedelcu 0 Reputation points

I'm trying to add a user on a Delivery management list but I get an error preventing me to add the user.

I've changed the display name and even tried to add another random user, but it still gives the error.

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.
7,345 questions
0 comments No comments
{count} votes

1 answer

Sort by: Most helpful
  1. Jake Zhang-MSFT 1,075 Reputation points Microsoft Vendor

    Hi Mihai Nedelcu,

    According to your problem description, I suggest you can use the following solutions:

    1. When adding users, avoid using attributes like display names or aliases. Instead, use unique-valued properties such as email addresses or User Principal Names (UPNs). These properties ensure that there’s no ambiguity when identifying recipients.
    2. Make sure the email address entered is correct and matches the user's actual email address. If the e-mail address is incorrect, the system will not be able to add the user to the list.

    If you have any questions about the above method, feel free to comment me and I'll be happy to provide you with a solution to your problem.