simple mail transport protocol

例句：

1. 1. The Simple Mail Transfer Protocol is used to send emails between different email systems.
   简单邮件传输协议用于不同电子邮件系统之间的电子邮件发送。
2. 2. The Simple Mail Transfer Protocol is a standard that defines the format and structure of email messages.
   简单邮件传输协议是一个标准，定义了电子邮件消息的格式和结构。
3. 3.The Simple Mail Transfer Protocol is widely used in email services and web applications.
   简单邮件传输协议在电子邮件服务和网页应用程序中广泛使用。