hi

We are finding that many genuine emails are being sent to our customers without the domain pointing to an A or MX record resulting postfix giving error Sender address rejected. Domain not found

This spam in most cases but in  some rare cases these are genuine emails.

We read online that we can whitelist such domains by mentioning the domain name in
check_sender_access pcre:/etc/postfix/sender_access.pcre file.

abc.com OK

We tried but this does not work.

Help required please.

# Sender restrictions
smtpd_sender_restrictions =
    check_sender_access pcre:/etc/postfix/sender_access.pcre
    reject_unknown_sender_domain
    reject_non_fqdn_sender
    reject_unlisted_sender
    permit_mynetworks
    permit_sasl_authenticated
    reject_sender_login_mismatch
    reject_unknown_reverse_client_hostname

thanks
rajesh