使用 Telnet 连接 GreenMail 模拟邮件服务器 (测试 SMTP / IMAP 连接)

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要求

  • GreenMail Standalone

  • 本地 Apache 服务器

下载

  1. 从 GreenMail 官网直接下载

  2. 使用命令行指令下载：

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cd /home/user/

wget https://repo1.maven.org/maven2/com/icegreen/greenmail-standalone/2.1.0-alpha-1/greenmail-standalone-2.1.0-alpha-1.jar

下载完成以后从终端运行.jar文件：

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java -Dgreenmail.smtp.timeout=120000 -Dgreenmail.smtp.hostname=0.0.0.0 -Dgreenmail.smtp.port=3025 -Dgreenmail.imap.hostname=0.0.0.0 -Dgreenmail.imap.port=3143 -jar /path/to/file/greenmail-standalone-2.1.0-alpha-1.jar

-Dgreenmail.smtp.timeout：为防止 SMTP 服务器超时，把超时时常设置为 120000 毫秒

-Dgreenmail.smtp.hostname, Dgreenmail.smtp.port：设置 SMTP 地址和端口

-Dgreenmail.imap.hostname, -Dgreenmail.imap.port：设置 IMAP 地址和端口

连接 SMTP 服务器

开启 Telnet 进程，连接到 SMTP 服务器的 3025 端口：

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telent localhost 3025

# 因为是模拟握手，所以服务器地址就是本地域名
$ telnet localhost 3025
Trying ::1...
Connected to localhost.
Escape character is '^]'.
220 /0:0:0:0:0:0:0:1 GreenMail SMTP Service v2.1.0-alpha-1 ready
421 Service shutting down and closing transmission channel (socket timeout, SO_TIMEOUT: 30000ms)

握手成功了！接下里可以输入四字指令和 SMTP 服务器交流：

C: HELO localhost
S: 250-/0:0:0:0:0:0:0:1
   250 AUTH PLAIN LOGIN
C: MAIL FROM: <example@email.com>
S: 250 OK
C: RCPT TO: <example@email.com>
S: 250 OK
C: DATA
S: 354 Start mail input; end with <CRLF>.<CRLF>
C: HELLO THERE
   THIS IS USER SPEAKING
   .
S: 250 OK
C: QUIT
S: 221 /0:0:0:0:0:0:0:1 Service closing transmission channel
   Connection closed by foreign host.

解释一下这些缩写是什么意思：

HELO: hello

RCPT: recipient

CRLF: carriage return & line feed

连接 IMAP 服务器

认证阶段

  2023-10-09 14:59:25,387 INFO
  user.UserManager| Created user login example@email.com for address example@email.com with password
  example@email.com because it didn't exist before.

  $ telnet localhost 3110
  +OK POP3 server ready
  user example@email.com
  +OK
  pass example@email.com
  +OK user successfully logged on

交易阶段

  C: list
  S: 1 498
  S: 2 912
  S: .
  C: retr 1
  S: (blah blah ...
  S: .................
  S: ..........blah)
  S: .
  C: dele 1
  C: retr 2
  S: (blah blah ...
  S: .................
  S: ..........blah)
  S: .
  C: dele 2
  C: quit
  S: +OK POP3 server signing off

用户在这个阶段可以给邮件添加标记，被添加删除标记的邮件将在最后的更新阶段被删除。