增加防止发件人身份伪造的配置：

# smtpd related config smtpd_recipient_restrictions =   permit_mynetworks,   permit_sasl_authenticated, #  reject_non_fqdn_hostname,   reject_non_fqdn_sender,   reject_non_fqdn_recipient,   reject_unauth_destination,   reject_unauth_pipelining,   reject_invalid_hostname

smtpd_sender_restrictions =   permit_mynetworks,   check_recipient_access hash:/etc/postfix/local_recipient,   permit_sasl_authenticated,   reject_sender_login_mismatch,   reject_authenticated_sender_login_mismatch,   reject_unauthenticated_sender_login_mismatch,   reject_unknown_sender_domain

# SMTP AUTH config here broken_sasl_auth_clients = yes smtpd_sasl_auth_enable = yes smtpd_sasl_security_options = noanonymous

　　补充：

　　配置extmail不允许伪造不存在的本地邮件地址发邮件,不允许并仿冒他人邮件地址发送邮件

　　cd /etc/postfix/

　　cat >mysql_virtual_sender_maps.cf<

　　user = extmail

　　password = extmail

　　hosts = localhost

　　dbname = extmail

　　table = mailbox

　　select_field = username

　　where_field = username

　　additional_conditions = AND active = 1

　　EOF

　　vim main.cf

　　smtpd_sender_login_maps =

　　mysql:/etc/postfix/mysql_virtual_sender_maps.cf

　　smtpd_sender_restrictions =

　　permit_mynetworks,

　　reject_sender_login_mismatch,

　　reject_authenticated_sender_login_mismatch,

　　reject_unauthenticated_sender_login_mismatch使配置生效

　　postfix reload