Problem with "closed" user

Problem with "closed" user

Hi there, 

I've got a problem with one of our User accounts in the zoho CRM. The User has the status "closed" and email-address states: "user does not exist". The problem is, that the user counts against the total for active users. Is there any way to reactivate this user with the existing email adress? (There is no acitvation link or any action I can take)

Thanks for your help
Carsten