A customer has POA-managed Hosted Exchange subscriptions with the service users and mailboxes like in the example below:
The key point - email address of one user (firstname.lastname@example.org) is the same as login name of another user.
If a customer try to grant the 'Send As' permission for the mailbox email@example.com on the mailbox firstname.lastname@example.org then POA task 'Grant send permissions for mailbox' fails with the following error message:
There are multiple users or groups matching the identity "email@example.com". Please specify a unique value.
See more detailed diagnostics in the example below:
Task name Grant send permissions for mailbox 'johndoe' (id=273) Last execution output Provisioning request failed. Error in 'SW Managed Exchange.SetDeliveryPermissions'. Exception calling "Execute" with "3" argument(s): "There are multiple users or groups matching the identity "firstname.lastname@example.org". Please specify a unique value.
The reason of the problem is that there are two objects referencing the same value in Active Directory:
Service user #394 has login name email@example.com
- Service user #395 has email address firstname.lastname@example.org
POA is using the Add-Permission Exchange cmdlet to grant permissions on the mailbox, the exact command looks like this:
Add-ADPermission -Identity "CN=johndoe,OU=S001000101,OU=Provider,OU=Hosting,DC=hosting,DC=local" -User "email@example.com" -ExtendedRights Send-As -Confirm
The Exchange cmdlet Add-Permission found two target objects referencing firstname.lastname@example.org and fails to grant the Send-As permission.
Resolve conflict with two objects referencing the same value in AD, e.g. temporarily change login name of service user whose login is the same as email address of another service user, process failed POA task after that.
This problem was fixed in scope of POA-65266 in 5.5 and in 5.4.14..