1 前言
筆者有時候調試郵件服務器需要使用Telnet直接去操縱IMAP與SMTP的服務，所以整理此文。
2 最佳實踐
2.1 IMAP服務
2.1.1 使用Telnet鏈接IMAP服務
telnet imap.cmdschool.org 143
信息顯示如下，
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 登錄郵箱
a01 login username password
登錄成功你將會看到如下提示，
a01 OK LOGIN completed
2.1.3 列出所有信箱
a02 list "" *
將會看到如下提示，
* LIST (\HasNoChildren) "\\" Drafts
* LIST (\Noinferiors \HasNoChildren) "\\" Inbox
* LIST (\HasNoChildren) "\\" Sent
[...]
a02 OK LIST completed
2.1.4 退出協議
a03 logout
命令顯示如下，
* BYE logging out
Connection closed by foreign host.
2.1 SMTP服務
2.1.1 使用Telnet鏈接SMTP服務
telnet smtp.cmdschool.org 25
信息顯示如下，
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 聲明發件人
mail from:will@cmdschool.org
信息顯示如下，
250 will@cmdschool.org... Sender OK
2.1.4 聲明主送人
rcpt to:free@cmdschool.org
信息顯示如下，
250 free@cmdschool.org.. Recipient OK
2.1.5 聲明郵件正文
data
可見如下提示，
354 Enter message, end with "." on a line by itself
根據向導輸入郵件正文與結束符號，
test
.
信息顯示如下，
250 Message accepted for delivery
參閱文檔
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