先把sasl认证加上, 否则用不了几天就会被列出黑名单了.
然后main.cf按下修改, 愿意的话再加上几个RBL过滤
smtpd_recipient_restrictions =
permit_sasl_authenticated,
reject_unknown_recipient_domain,
reject_non_fqdn_recipient
reject_non_fqdn_hostname,
reject_non_fqdn_sender,
reject_non_fqdn_recipient,
reject_unauth_destination,
reject_unauth_pipelining,
reject_invalid_hostname,
permit
smtpd_sasl_auth_enable = yes