上一篇，提到 使用telnet命令行访问邮件smtp发件服务器发送邮件 ，那如何使用telnet访问邮件收件服务器呢？在该文末，提到登录方式相同，但其实不然。
📧 腾讯企业邮箱登录方式
经过测试，访问腾讯企业邮件，确实可以通过auth login来登录：
telnet pop.exmail.qq.com 110
auth login
xxx
xxx🔧 自建James服务器登录方式
但我们发现访问我们自建的james服务器则不行，而需要使用下面命令形式来登录：
USER user1
+OK
PASS pass1
+OK Welcome user1说明：
上述示例user1不带邮箱后缀，可能与服务器邮箱设置有关，pass1是密码明文。
📋 POP3命令详细说明
| Command | Description | Example |
|---|---|---|
| USER [username] | 1st login command | USER Stan |
| +OK Please enter a password | ||
| PASS [password] | 2nd login command | PASS SeCrEt |
| +OK valid logon | ||
| QUIT | Logs out and saves any changes | QUIT |
| +OK Bye-bye. | ||
| STAT | Returns total number of messages and total size | STAT |
| +OK 2 320 | ||
| LIST | Lists all messages | LIST |
| +OK 2 messages (320 octets) | ||
| 1 120 | ||
| 2 200 | ||
| … | ||
| LIST 2 | ||
| +OK 2 200 | ||
| RETR [message] | Retrieves the whole message | RETR 1 |
| +OK 120 octets follow. | ||
| *** | ||
| DELE [message] | Deletes the specified message | DELE 2 |
| +OK message deleted | ||
| NOOP | The POP3 server does nothing, it merely replies with a positive response. | NOOP |
| +OK | ||
| RSET | Undelete the message if any marked for deletion | RSET |
| +OK maildrop has 2 messages (320 octets) | ||
| TOP [message] [number] | Returns the headers and number of lines from the message | TOP 1 10 |
| +OK | ||
| *** |