Use of "@" how login in the name

[Boletim GMX]

Hi all,   I have a question regarding cyrus authentication:   If I create a user with the Web-cyradm, the email address is [EMAIL PROTECTED] but for the login with IMAP/POP/SMTP, the user must use "name.domain.com".   Can I change this so the user can log in with your email address exactly - @?   Thanks for any help. Julio