add a new ftp user webmaster@my-domain.com or postmaster@ or....

On an existing virtual server with or without mail aliases, it is not possible to add a new ftp user called 'webmaster@my-domain.com' or 'postmaster@my-domain.com'

The users appear in the list as if all was ok.

Virtualmin shows no error, the user appears in /etc/passwd but he cannot log @ftp.

Creating others ftp users like 'test@my-domain.com' works great. But if the username contains something that looks like a mail alias, he won't be able to log @ftp/

Last virtualmin and webmin versions
OS : Centos 5.3, VSFTPD

Status: 
Closed (fixed)