What is Simple Mail Transfer Protocol?

Simple Mail Transfer Protocol (SMTP) is a Application Layer protocol in the Email category. Standard protocol for sending email between mail servers. Handles message routing, delivery, and relay across the internet.

What port does SMTP use?

SMTP uses port 25, 465, 587 by default. The protocol is defined in RFC 5321.

SMTP :25

Simple Mail Transfer Protocol

Application Layer — Email

协议概览

全称 Simple Mail Transfer Protocol

缩写 SMTP

OSI 层 Application Layer

类别 Email

默认端口 25, 465, 587

RFC RFC 5321

关于 SMTP

Standard protocol for sending email between mail servers. Handles message routing, delivery, and relay across the internet.

Application Layer Email 端口 25, 465, 587

标准参考

SMTP定义于互联网工程任务组（IETF）发布的RFC 5321中。RFC是互联网协议的官方标准文档，可免费公开查阅。

Simple Mail Transfer Protocol

协议概览

关于 SMTP

标准参考

相关协议 — Application Layer