SSRS: Failure sending mail: The user or group name ‘Domain\UserName’ is not recognized.Mail will not be resent.

Just ran into this one. If an SSRS report user comes to you indicating that they’ve attempted to created a subscription and, although it allowed the subscription to be created, the report subscription failed to be sent via email with the following Status:

Failure sending mail: The user or group name ‘Domain\UserName’ is not recognized.Mail will not be resent.

When troubleshooting, I found that the subscription owner account name did NOT match the Windows account name of the user contacting me. In the end, the root cause was a domain name change for the affected user. The login name on the SQL Server hosting the ReportServer database still had the old domain name for the user and used that name in the subscription setup, which failed when the credentials were used to generate and send the emailed report.

The quick fix was to execute the following via our SQL Server CMS (Central Mgmt Server):

IF EXISTS (SELECT 1 FROM sys.server_principals WHERE name = ‘DOMAIN\OldUserName’)
BEGIN
ALTER LOGIN [DOMAIN\OldUserName]
WITH NAME = [DOMAIN\NewUserName]
END

Hope that helps if you run into this situation in your travels…

-Patrick