Crm 2011, Email id edited from the domain email id

Hi All,

My customer facing a unique issue , stating it below . Your help is most appreciated

CRM 2011, instance: A user is not able to log in to Prod instance with domain credentials, the same user is able to login to the test instance with the same domain credentials. The only aberration found was that the Email id in production did not match to the domain.com email id. The status shows " Pending approval" as well.

Is this a reason why the user cannot get authenticated?

There are sufficient licenses available for even new users to be added.

Any pointers will be most helpful.

regards,

Prashanth