一般都是用手工去telnet 邮件服务器 25，来进行交互测试。不过现在有个网址可以帮我进行测试：
http://www.abuse.net/relay.html
只要输入您邮件服务器的ip地址，它就会自动进行4次以上的测试，最后得出结论，诸如：
THIS MAY OR MAY NOT MEAN THAT IT'S AN OPEN RELAY.
Some systems appear to accept relay mail, but then reject messages internally rather than delivering them, but you cannot tell at this point whether the message will be relayed or not.
You cannot tell if it is really an open relay without sending a test message; this anonymous user test DID NOT send a test message.
