1 qmail-smtpd     Receive message by SMTP from another host:

     2                    

     3                    MAIL FROM:<spammer@aol.com>

     4                    RCPT TO:<bill@irs.gov>

     5                 

     6                 Is $RELAYCLIENT set? No.

     7                 Is irs.gov in rcpthosts? No.

     8                 Reject RCPT.