Event ID - 10000

Event Id10000
DescriptionA message was not delivered because the following address was not unique:<testuser@domain.com>
Event InformationAccording to Microsoft:
This issue can occur because addresses must be unique across an Exchange Server organization, and so an address (for example, testuser@testdomain.domain.com) can only exist once in the organization. However, if the same address is created on two separate servers before replication is established or before replication has time to finish, it is possible to have two objects with the same address.
To resolve this issue, export the global address list from the server that is producing the error. Make sure that you include mailboxes, distribution lists, and custom recipients, as well as hidden objects. Also make sure that "E-mail Addresses" and "Secondary-Proxy-Addresses" exist in the header of the export file with the other fields to be exported. Import the .csv file that is created into Microsoft Excel and search for the location of the conflicting directory entries. You can then alter or delete the objects, as appropriate.
Reference LinksFinding Ambiguous Recipients or Recipients That Have Duplicate Addresses

Catch threats immediately

We work side-by-side with you to rapidly detect cyberthreats
and thwart attacks before they cause damage.

See what we caught

Did this information help you to resolve the problem?

Yes: My problem was resolved.
No: The information was not helpful / Partially helpful.