SMTP认证已运行，为何仍能用虚假账号发信

jianblog

测试环境如下：一台虚拟机redhat，postfix+dovecot+saslauth.
saslauth相关配置文件如下
1）# more /etc/sysconfig/saslauthd
SOCKETDIR=/var/run/saslauthd
MECH=shadow
FLAGS=
2）# /usr/lib64/sasl2/smtpd.conf
pwcheck_method: saslauthd
sasl_mech_list: PLAIN

3）main.cf 关于认证部分的参数：
smtpd_sasl_auth_enable = yes
smtpd_sasl_security_options = noanonymous
#broken_sasl_auth_clients = yes smtpd_client_restrictions = permit_sasl_authenticated smtp_delay_reject = yes  smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, permit_auth_destination, reject 4）测试认证 # testsaslauthd -u eagle -p eagle 0: OK "Success." telnet测试如下 telnet localhost 25 Trying 127.0.0.1... Connected to mail.localhost (127.0.0.1). Escape character is '^]'. 220 mypc.com ESMTP Postfix ehlo localhost 250-mypc.com 250-PIPELINING 250-SIZE 10240000 250-VRFY 250-ETRN 250-AUTH PLAIN LOGIN 250-ENHANCEDSTATUSCODES 250-8BITMIME 250 DSN 问题： 我从另一台主机安装foxmail可以用系统账号收发信，如果选定smtp需要认证，则连接时弹出提示要求输入密码；而如果不选，即便用一个虚假的用户也能通过邮件server向真实的系统用户发送信件，这点不明白为什么？希望哪位指点