对方邮件服务器启用灰名单，会导致邮箱暂时无法验证出结果，一般灰名单时间5分钟

什么是邮件灰名单

今天介绍Postgrey灰名单，网址http://postgrey.schweikert.ch/

当我们发邮件的时候，有时会收到：
 

You came here probably after seeing a mail of yours being rejected with a message like this:

Greylisted for 300 seconds (see http://postgrey.schweikert.ch/help)

The mail server generating this error message is using a system called Greylisting to filter spam and viruses. It relies on Mail Servers behaving according to the standards and usually doesn't require any action by the user. Your mails should only possibly be delayed.

If you see this error message while sending a mail, it probably means that you did something wrong: the configured mail server should trust your machine and thus not apply greylisting at all.

Make sure that you did turn on encryption and authentication for the SMTP server in your mail client. Ask your system administrator if you are not sure about how to configure it.

See this page for a description about how Greylisting works.

Postgrey - Postfix灰名单策略服务器。
Postgrey是一个Postfix策略服务器，实现由David Schweikert开发的灰名单 。

当Postfix通过SMTP收到邮件传递请求时，将构建三元组CLIENT_IP / SENDER / RECIPIENT。如果这是第一次看到这个三元组，或者如果第一次看到三元组，不到5分钟前，则邮件会被暂时错误拒绝。希望垃圾邮件发送者或病毒不会在以后再次尝试，因为每个RFC都需要它。

邮件灰名单也会导致邮箱暂时无法验证出结果，此类邮箱，建议过5分钟再验证。