in 1.3 I have created some accounts for testing with the same email address and found that the second account cannot login through the customer portal.
I think this is because of the problem discussed here:
My users use email address for both login and email (they are the same and that's the way we like it to be)
So given that there is a deleted user with the same login/email I don't think setting the portal settings to login will help.
I need to know how I can manually delete the deleted user from the database and/or if this happens automatically after a certain time?