POP3-supported command set for Exchange Server 5.0 (161116)

MORE INFORMATION

Listed below are the commands along with the functionality that each command provides.

• Command: USER
  
  Description: Used to specify the name of the user you wish to logon as. For TR1, it can be specified in the form of either:

  USER username -or- USER domain\username

  Additionally, if the mailbox name for the user logging on differs from that of the username, the log on may be stated in the form of:

  USER domain\username/mailboxname

  
  
  
• Command: PASS
  
  Description: This is the Windows NT domain password of the user who is logging on.
  
  Usage:

  PASS password

• Command: LIST
  
  Description: Used to list messages and their combined size. For example, invoking the LIST command with no parameters will return 2 +OK messages (320 octets). This means that there are two messages in the user's mail drop taking a total of 320 octets of space. To see an individual message simply type:

  LIST N

  where N is a number between one and the number of messages originally returned by the LIST command.
  
  
• Command: QUIT
  
  Description: Quits the current telnet session and deletes any messages marked for deletion.
  
  
• Command: UIDL
  
  Description: Returns the Unique ID Listing for a message. This command invoked in the form of either:

  UIDL -or- UIDL N

  where N is the message number of the UIDL that the user wants to view. Exchange Server determines this unique value in the following fashion:

  The BASE64 value of the 64-bit Message ID and then the 128 GUID for that message. If the command is invoked without arguments, a numerical listing of all messages and their associated UIDLs is displayed.

• Command: APOP
  
  Description: Not Supported. APOP is an alternative method of authentication. This is one of the optional POP3 commands.
  
  
• Command: RETR
  
  Description: Used to Retrieve a message from the server.
  
  Usage:

  RETR N

  where N is a number between 1 and the last number returned by the LIST command. This command may not be used to retrieve a message that has been marked as deleted.
  
  
• Command: STAT
  
  Description: The STAT command is similar to the LIST command in that the server will return the number of messages in the Mail drop along with the total space (in octets) that those messages occupy. However, this is all the information returned by this command. To display messages, either the RETR or LIST commands must be invoked.
  
  
• Command: DELE
  
  Description: This command is used to delete a message. It does not actually delete the message but simply sets a delete flag. The message is actually deleted when the client gracefully breaks the connection to the server using the QUIT command. In the case where there is a crash or immediate connection termination by the client, the messages are not deleted.
  
  Usage:

  DELE N

  where N is the number of the message provided by the LIST command.
  
  
• Command: NOOP
  
  Description: A Null or NO OPeration. In this case, the server does nothing.
  
  
• Command: RSET
  
  Description: Used by the client to reset the state of messages marked for deletion.
  
  
• Command: TOP
  
  Description: This command is used to display both the header for a message and a given number of lines for that message. This command is used in the form of:

  TOP XY

  where X is the message number the user wants to view and Y is the number of lines in that message to be displayed. The server should return the headers for the message followed by a blank line and then the Y number of lines for that message.
  
  
• Command: AUTH
  
  Description: This is an IMAP4 command that is part of the POP specification from RFC1734. It allows for the use of alternative IMAP4 authorization techniques.

Note A POP3 client uses standard SMTP to send messages. The POP3 command set listed in this article is to receive messages only.

For more information on POP3, please refer to RFC 1725, RFC 1734 and RFC 1939. You can locate these and other RFCs at the following Web site: