1) Configure should be run after drweb-smf binary has been installed 2)
-zACTION flag changed from d to c, because with -zd drweb-smf discards
emails with empty reverse-path (MAIL FROM: SMTP command which corresponds
to Return-Path: envelope header) rather than emails with empty From:
message header. According to RFC 2821 MTAs use empty reverse-path for
rejection notifications and many other mail robots also do that.