smtp。 gmail.com 需要 TLS。 Windows随附的基本telnet客户端不知道如何与服务器协商TLS。您可能要改用openssl，它可以协商TLS。参见 http://www.madboa.com/geek/openssl/#cs-smtp 有关如何执行此操作的示例。

smtp.gmail.com requires TLS. The basic telnet client that comes with windows does not know how to negotiate TLS with a server. You may want to use openssl instead, which is able to negotiate TLS. See http://www.madboa.com/geek/openssl/#cs-smtp for an example of how to do this.