1 前言
笔者有时候调试邮件服务器需要使用Telnet直接去操纵IMAP与SMTP的服务，所以整理此文。
2 最佳实践
2.1 IMAP服务
2.1.1 使用Telnet链接IMAP服务
telnet imap.cmdschool.org 143
信息显示如下，
Trying 113.96.209.109...
Connected to imap.cmdschool.org.
Escape character is '^]'.
* OK Domino IMAP4 Server Release 9.0.1FP3 ready Tue, 3 Sep 2019 09:19:36 +0800
2.1.2 登录邮箱
a01 login username password
登录成功你将会看到如下提示，
a01 OK LOGIN completed
2.1.3 列出所有信箱
a02 list "" *
将会看到如下提示，
* LIST (\HasNoChildren) "\\" Drafts
* LIST (\Noinferiors \HasNoChildren) "\\" Inbox
* LIST (\HasNoChildren) "\\" Sent
[...]
a02 OK LIST completed
2.1.4 退出协议
a03 logout
命令显示如下，
* BYE logging out
Connection closed by foreign host.
2.1 SMTP服务
2.1.1 使用Telnet链接SMTP服务
telnet smtp.cmdschool.org 25
信息显示如下，
Trying 113.96.232.106...
Connected to smtp.cmdschool.org.
Escape character is '^]'.
220 smtp.cmdschool.org ESMTP Service (IBM Domino Release 9.0.1FP3) ready at Tue, 3 Sep 2019 09:46:31 +0800
2.1.2 helo指令
helo cmdschool.org
250 smtp.cmdschool.org Hello cmdschool.org ([113.96.232.106]), pleased to meet you
2.1.3 声明发件人
mail from:will@cmdschool.org
信息显示如下，
250 will@cmdschool.org... Sender OK
2.1.4 声明主送人
rcpt to:free@cmdschool.org
信息显示如下，
250 free@cmdschool.org.. Recipient OK
2.1.5 声明邮件正文
data
可见如下提示，
354 Enter message, end with "." on a line by itself
根据向导输入邮件正文与结束符号，
test
.
信息显示如下，
250 Message accepted for delivery
参阅文档
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