Antispam with authorization from POP3 server.

[Michael A. Borisov]

Hello. It is necessary to me to authorize everyone, who tries to send mail
through my SMTP server. I want to use for this purpose authorization of a
POP3 server. I want that authorization was requested for the user, which is
specified in a field 'from:' of the head of the sent message. How it is
possible to solve this problem?

Thank you in advance,
Michael Borisov.