Use smtpd_sender_restrictions
da seguinte forma:
main.cf
smtpd_sender_restrictions =
# Reject some domains because they send annoying spam
check_sender_access hash:/etc/postfix/sender_access
# Other useful things to do:
warn_if_reject reject_non_fqdn_sender
reject_unknown_sender_domain
# Default PERMIT
/ etc / postfix / sender_access
# annoying spammer domains
businessleadsonlinemail.com REJECT
527media.com REJECT
aweberer.com REJECT
pathcom.com REJECT
Não se esqueça de postmap
do seu novo banco de dados de acesso!