Filter outgoing email


New Email
Hi there,

I've got a qmail server that is working from several years. I manage about 15 domains on it and everything works fine except that I would like to block some spammer from send mail even if they are authenticated.

I need to leave authenticated user be able to send email from across the world since they travel a lot, so I can't filter from IP, etc. but I would like that if a user is authenticated with an email address he can't send email with an address with a different domain.

For example: authenticates with his email client (Outlook, Thunderbird, etc.) with correct username and password and send email to,, etc. from

But I would like to block his mails if he try to send mail from authenticated with username

Is it possbile?

Many thanks in advance to anybody who will help me!