thanks so much for your reply, the dkim and SPF is working fine,
i checked the log, the error is:
Dec 4 20:07:51 www postfix-local[59170]: postfix-local: from=MAILER-DAEMON,
[email protected], dirname=/var/qmail/mailnames
Dec 4 20:07:51 www postfix-local[59170]: Unable to get sender domain by...