The e-mail address contains illegal characters

When ı am creating the user
ı have that problem
The e-mail address 'sertuncyahoo.com' contains illegal characters
how can ı fix it

Thank you
What email address are you entering? The email address needs to at least include an @ symbol. Otherwise, make sure that you're running the latest version of the FBA Pack, as earlier versions did have issues validating certain email addresses.