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E-mail: Ouyang@china-pub.com
Translator: Hu Weilong (Along_2000 Along_2000@263.net)
Translation time: 2001-3-19
Copyright: This Chinese translation copyright belongs to China Interactive Publishing Network. Can be used for non-commercial use free reprint, but the translation and copyright information of this document must be retained.
Network Working Group J. K. Reynolds
Request for Comments: 918 ISI
October 1984
Post office protocol
(RFC-918 - Post Office Protocol)
The status of this document:
This document puts forward a simple protocol that implements a workstation from the mail server dynamically charged the mail. This document proposes an agreement for Internet community for ARPA (Advanced Research Projects Agency). It requires further discussion and recommendations to conduct further improvements.
1. Introduction:
The POST Office Protocol (POP) is to allow workstation users to collect messages from the mail server. The workstation is sent to the mail server expects to be implemented via Simple Mail Transfer Protocol (SMTP) protocol. For further information, see RFC-821, RFC-822.
This document is in the test phase, and this agreement is based on TCP implementation.
2. protocol:
This Agreement is: The mail server starts listening to the connection. When the connection is opened, the server sends a greeting information and waits for the command. When the command is received, the server executes and returns a response.
The client opens a connection. Waiting for greetings. Then send the user and pass command to confirm the permissions of the mailbox. The client sends a RDEL command (reading and deleting all messages in the mailbox) or the retr command (only simply reading the message from the mailbox). The server opens the mailbox, lock it. Then return to the client to all the characters of all messages in the mailbox. The client sends the RCEV command to request mail data. The server returns the corresponding mail data. When all of the messages are all received, the client sends the RCVD command. If the process begins to be a RDEL command sent by the client, the server will delete all messages at this time. In that case, the server will turn off the mailbox and unlock. The client sends a Quit command to terminate the session.
generally:
Client server
---------- ------------
Listen connection
Open connection ->
* OK
Waiting for a command
User fred ->
* OK
Waiting for a command
Pass Password ->
* OK
Waiting for a command
(Open and lock the mailbox)
RDEL Mailbox ->
* #xxx
Waiting for a command
RCEV ->
* Send a copy of a message
Waiting for a command
RCVD -> (remove mail from the mailbox, unlock and close the mailbox)
* OK
Waiting for a command
Quit ->
* OK
Turn off the connection -> <- Close the connection to the new connection (return to start)
Corresponding to commands and responses
Command and reply summary
Command response
-----------------------------------
User name ok
Pass Password -Error
Retr Mailbox #xxx
RCEV
RCVD
Quit
NOOP
Rset
User name
This command is used to identify the server flag. He must have a pass command later.
Possible response: " ok" or "-err"
Pass Password
The pass command is used to send the user's verification password. User and pass commands are used for server control to access the mailbox.
Possible response: " ok" or "-err"
Retr Mailbox
This command will start a reading email process. The retrign is used to read messages in the mailbox without removing them. He must follow RCEV command later
Possible response: " xxx" or "-err"
RDEL Mailbox
This command will start a reading email process. The retr command is used to read the mail in the mailbox and delete them. He must follow RCEV command later
Possible response: " xxx" or "-err"
RCEV
This command is used to confirm that the client is ready to accept mail data, and he must follow the RCVD command later.
Possible response: " ok" or connection interrupt
RCVD
This command is used to confirm that the client has received and accepted the mail data. The RCVD command terminates the mail reading process. If it is a RDEL process, it is not necessary to delete. This will be indicated by sending an error reply.
Possible response: " ok" or "-err"
Quit
This command indicates that the client has completed this session, and the server will send a " OK" response and close the connection.
Possible response: " ok" then close the connection
NOOP
This is a command that does not complete any operation, except for the server sends an OK reply, it does not trigger any operations on the server.
Possible response: " ok"
Rset
This command will trigger the server interrupt the current process and return a wait command (one of RDEL, RETR, Quit, NOOP or RSET) When a process is broken, the server must pay attention to the correct closing email address and unlock the mailbox.
Possible response: " ok"
3. Thank you
I would like to Acknowledge The Contributions of Jon Postel, Joel Goldberger, Dale Chase, and Michael Butler In The Development of the Post Office Protocol.
4. reference:
[1] Postel, J., "Simple Mail Transfer Protocol", RFC-821, USC / INFPATION sciences institute, August 1982.
[2] CROCKER, D., "Standard for the format of arpa-Internet text message", RFC-822, University of Delaware, August 1982.
Illustration:
- - - -
Open | | OK | | | | OK
-----> | s | - -> | c | ------> | s | ------> | c | ------> | s | ->
| | ^ | | User | | | | PASS | |
- | - - - - |
| | -Err | -err |
| V v |
<----------- -------------- --------------- ----- |
| | |
V - --- |
---> | | quit | | OK |
| C | ------> | s | -----> Close |
---> | | | | | |
^ - --- |
| V
------------------------------------------------------------------------------------------- -------------
| ^
| - - - - - - |
| | | RETR | | | | DATA | | | OK |
-> | c | ----> | s | -----> | c | ----> | s | ----> | c | ----> | s | >
| | | | Or | | | | | | | | ^
| - RDEL - - - - |
| | | -ERR | | | | -ERR || V | V | | | |
------------- | Abort | | |
| V v v |
| ---------------------------------- ----->
| V
| - -
| | | | RSET | | OK
---> | c | ------> | s | ----->
| | | | | | |
| --- --- |
| V
--------------------------
| ^
| --- --- |
| | | | NOOOP | | OK |
---> | c | ------> | s | ----->
| | | | | |
- -
RFC-918 Post Office Protocol Post Office Agreement
4
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