POP3指令：
user name输入用户名
pass ****输入密码
stat 看总共多少封信件,多少字节
list 列出每封信件的字节数
retr n 读第n封信
rset 重置
uidl n down第n封信
top n m 读第n封信的信头，但我不知道m是什么意思，通常令m=1
dele n 删除第n封信
noop 是空指令，防止被服务器踢线。
last 是查看被取走的邮件的最高序数。
quit 退出
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SMTP指令：（懒得写了，直接从服务器上copy了一把）
220 xxxx.xxxx.edu.cn ESMTP Sendmail 8.9.3/8.8.7; Sat, 28 Oct 2000 19:14:09 +0800
help
214-This is Sendmail version 8.9.3
214-Topics:
214- HELO EHLO MAIL RCPT DATA
214- RSET NOOP QUIT HELP VRFY
214- EXPN VERB ETRN DSN
214-For more info use "HELP <topic>".
214-To report bugs in the implementation send email to
214- sendmail-bugs@sendmail.org.
214-For local information send email to Postmaster at your site.
214 End of HELP info
help helo
214-HELO <hostname>
214- Introduce yourself.
214 End of HELP info
help ehlo
214-EHLO <hostname>
214- Introduce yourself, and request extended SMTP mode.
214-Possible replies include:
214- SEND Send as mail [RFC821]
214- SOML Send as mail or terminal [RFC821]
214- SAML Send as mail and terminal [RFC821]
214- EXPN Expand the mailing list [RFC821]
214- HELP Supply helpful information [RFC821]
214- TURN Turn the operation around [RFC821]
214- 8BITMIME Use 8-bit data [RFC1652]
214- SIZE Message size declaration [RFC1870]
214- VERB Verbose [Allman]
214- ONEX One message transaction only [Allman]
214- CHUNKING Chunking [RFC1830]
214- BINARYMIME Binary MIME [RFC1830]
214- PIPELINING Command Pipelining [RFC1854]
214- DSN Delivery Status Notification [RFC1891]
214- ETRN Remote Message Queue Starting [RFC1985]
214- XUSR Initial (user) submission [Allman]
214 End of HELP info
help mail
214-MAIL FROM: <sender> [ <parameters> ]
214- Specifies the sender. Parameters are ESMTP extensions.
214- See "HELP DSN" for details.
214 End of HELP info
help rcpt
214-RCPT TO: <recipient> [ <parameters> ]
214- Specifies the recipient. Can be used any number of times.
214- Parameters are ESMTP extensions. See "HELP DSN" for details.
214 End of HELP info
help data
214-DATA
214- Following text is collected as the message.
214- End with a single dot.
214 End of HELP info
help rset
214-RSET
214- Resets the system.
214 End of HELP info
help noop
help quit
help help
help vrfy
214-VRFY <recipient> （注：这里recipient可以是你的username）
214- Verify an address. If you want to see what it aliases
214- to, use EXPN instead.
214 End of HELP info
help expn
214-EXPN <recipient>
214- Expand an address. If the address indicates a mailing
214- list, return the contents of that list.
214 End of HELP info
help verb
214-VERB
214- Go into verbose mode. This sends 0xy responses that are
214- not RFC821 standard (but should be) They are recognized
214- by humans and other sendmail implementations.
214 End of HELP info
help etrn
214-ETRN [ <hostname> | @<domain> | #<queuename> ]
214- Run the queue for the specified <hostname>, or
214- all hosts within a given <domain>, or a specially-named
214- <queuename> (implementation-specific).
214 End of HELP info
help dsn
214-MAIL FROM: <sender> [ RET={ FULL | HDRS} ] [ ENVID=<envid> ]
214-RCPT TO: <recipient> [ NOTIFY={NEVER,SUCCESS,FAILURE,DELAY} ]
214- [ ORCPT=<recipient> ]
214- SMTP Delivery Status Notifications.
214-Descriptions:
214- RET Return either the full message or only headers.
214- ENVID Sender's "envelope identifier" for tracking.
214- NOTIFY When to send a DSN. Multiple options are OK, comma-
214- delimited. NEVER must appear by itself.
214- ORCPT Original recipient.
214 End of HELP info
user name输入用户名
pass ****输入密码
stat 看总共多少封信件,多少字节
list 列出每封信件的字节数
retr n 读第n封信
rset 重置
uidl n down第n封信
top n m 读第n封信的信头，但我不知道m是什么意思，通常令m=1
dele n 删除第n封信
noop 是空指令，防止被服务器踢线。
last 是查看被取走的邮件的最高序数。
quit 退出
###########################################################
SMTP指令：（懒得写了，直接从服务器上copy了一把）
220 xxxx.xxxx.edu.cn ESMTP Sendmail 8.9.3/8.8.7; Sat, 28 Oct 2000 19:14:09 +0800
help
214-This is Sendmail version 8.9.3
214-Topics:
214- HELO EHLO MAIL RCPT DATA
214- RSET NOOP QUIT HELP VRFY
214- EXPN VERB ETRN DSN
214-For more info use "HELP <topic>".
214-To report bugs in the implementation send email to
214- sendmail-bugs@sendmail.org.
214-For local information send email to Postmaster at your site.
214 End of HELP info
help helo
214-HELO <hostname>
214- Introduce yourself.
214 End of HELP info
help ehlo
214-EHLO <hostname>
214- Introduce yourself, and request extended SMTP mode.
214-Possible replies include:
214- SEND Send as mail [RFC821]
214- SOML Send as mail or terminal [RFC821]
214- SAML Send as mail and terminal [RFC821]
214- EXPN Expand the mailing list [RFC821]
214- HELP Supply helpful information [RFC821]
214- TURN Turn the operation around [RFC821]
214- 8BITMIME Use 8-bit data [RFC1652]
214- SIZE Message size declaration [RFC1870]
214- VERB Verbose [Allman]
214- ONEX One message transaction only [Allman]
214- CHUNKING Chunking [RFC1830]
214- BINARYMIME Binary MIME [RFC1830]
214- PIPELINING Command Pipelining [RFC1854]
214- DSN Delivery Status Notification [RFC1891]
214- ETRN Remote Message Queue Starting [RFC1985]
214- XUSR Initial (user) submission [Allman]
214 End of HELP info
help mail
214-MAIL FROM: <sender> [ <parameters> ]
214- Specifies the sender. Parameters are ESMTP extensions.
214- See "HELP DSN" for details.
214 End of HELP info
help rcpt
214-RCPT TO: <recipient> [ <parameters> ]
214- Specifies the recipient. Can be used any number of times.
214- Parameters are ESMTP extensions. See "HELP DSN" for details.
214 End of HELP info
help data
214-DATA
214- Following text is collected as the message.
214- End with a single dot.
214 End of HELP info
help rset
214-RSET
214- Resets the system.
214 End of HELP info
help noop
help quit
help help
help vrfy
214-VRFY <recipient> （注：这里recipient可以是你的username）
214- Verify an address. If you want to see what it aliases
214- to, use EXPN instead.
214 End of HELP info
help expn
214-EXPN <recipient>
214- Expand an address. If the address indicates a mailing
214- list, return the contents of that list.
214 End of HELP info
help verb
214-VERB
214- Go into verbose mode. This sends 0xy responses that are
214- not RFC821 standard (but should be) They are recognized
214- by humans and other sendmail implementations.
214 End of HELP info
help etrn
214-ETRN [ <hostname> | @<domain> | #<queuename> ]
214- Run the queue for the specified <hostname>, or
214- all hosts within a given <domain>, or a specially-named
214- <queuename> (implementation-specific).
214 End of HELP info
help dsn
214-MAIL FROM: <sender> [ RET={ FULL | HDRS} ] [ ENVID=<envid> ]
214-RCPT TO: <recipient> [ NOTIFY={NEVER,SUCCESS,FAILURE,DELAY} ]
214- [ ORCPT=<recipient> ]
214- SMTP Delivery Status Notifications.
214-Descriptions:
214- RET Return either the full message or only headers.
214- ENVID Sender's "envelope identifier" for tracking.
214- NOTIFY When to send a DSN. Multiple options are OK, comma-
214- delimited. NEVER must appear by itself.
214- ORCPT Original recipient.
214 End of HELP info
