Simple Mail Transfer Protocol
Posted rsapaper
tags:
篇首语：本文由小常识网(cha138.com)小编为大家整理，主要介绍了Simple Mail Transfer Protocol相关的知识，希望对你有一定的参考价值。
https://en.wikipedia.org/wiki/Simple_Mail_Transfer_Protocol
https://zh.wikipedia.org/wiki/简单邮件传输协议
Simple Mail Transfer Protocol (SMTP) is an Internet standard for electronic mail (email) transmission. First defined by RFC 821 in 1982, it was last updated in 2008 with the Extended SMTP additions by RFC 5321—which is the protocol in widespread use today.
SMTP by default uses TCP port 25. The protocol for mail submission is the same, but uses port 587. SMTP connections secured by SSL, known as SMTPS, default to port 465 (nonstandard, but sometimes used for legacy reasons).
SMTP是一个“推”的协议，它不允许根据需要从远程服务器上“拉”来消息。要做到这点，邮件客户端必须使用POP3或IMAP。另一个SMTP服务器可以使用ETRN在SMTP上触发一个发送。
以上是关于Simple Mail Transfer Protocol的主要内容，如果未能解决你的问题，请参考以下文章
发送包含长 http-link 的 PHP mail() 时应该使用啥 Content-Transfer-Encoding？