Scenario 1: Employee left Organisation hence the Admin user deactivate the user & marked it obsolete. 6 months later, the employee rejoined the same Organisation and now when the Admin is trying to create a new user they are getting error.
Root cause: If user already existed in the tenant then the same email ID cannot be used to create a new user account.

If they are trying to create the user via Import Users then Admin will get below error in CSV(success report):
FailureReason
FailureReason
There is already an obsolete user in this account, please try activating it.
Solution: Admin should reactivate the obsolete user & then modify the user details(if required)
Scenario 2: User is deactivated in 1 account and the account is churned. Later on, the same client is onboarded again with a new account but they are unable to create the user since the email already existed(as deactivated user) in churned account.
Root cause: If user already existed in the tenant then the same email ID cannot be used to create a new user account even on a different tenant.
Solution: Connect with Billing.ops to mark the user as obsolete & then create the user in new Tenant.
