[otrs] Customer user without email address

Hello OTRS fans, Do you know the consequences when entering an invalid e-mail address during customer user creation ? We are using LDAP to autenticate our customer users, but there are a few who don't have an LDAP entry. For those, I would like to set up a second backend, using the OTRS database (customer_user table). The set up was fine, and I can create a user in the DB. BUT, this user does not have an e-mail address, which is mandatory. SO, I entered a wrong e-mail address. The user was successfully created, but I would like to know what kind of problems I might have. Thanks for your help on this. Regards, Regis