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Table Of Contents  The TCP/IP Guide
 9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)
      9  TCP/IP Key Applications and Application Protocols
           9  TCP/IP File and Message Transfer Applications and Protocols (FTP, TFTP, Electronic Mail, USENET, HTTP/WWW, Gopher)
                9  TCP/IP Electronic Mail System: Concepts and Protocols (RFC 822, MIME, SMTP, POP3, IMAP)
                     9  TCP/IP Electronic Mail Access and Retrieval Protocols and Methods
                          9  TCP/IP Post Office Protocol (POP/POP3)

Previous Topic/Section
POP3 General Operation, Client/Server Communication and Session States
Previous Page
Pages in Current Topic/Section
1
23
Next Page
POP3 Transaction State: Mail and Information Exchange Process and Commands
Next Topic/Section

POP3 Authorization State: User Authentication Process and Commands
(Page 1 of 3)

A session between a POP3 client and a POP3 server begins when the client sends a TCP connection request to the server. The connection is established using the standard TCP “three-way handshake”, and the POP3 session commences. The first of the three states of a POP3 session is the Authorization state, which is responsible for authenticating the POP3 client with the server.

When the session first enters this state, the server sends a greeting message to the client. This tells the client that the connection is alive and ready for the client to send the first command. An example of such a greeting would be:

+OK POP3 server ready

The client is now required to authenticate the user who is trying to access a mailbox. This both proves that the user has the right to access the server, and identifies the user so the server knows which mailbox is being requested.


Previous Topic/Section
POP3 General Operation, Client/Server Communication and Session States
Previous Page
Pages in Current Topic/Section
1
23
Next Page
POP3 Transaction State: Mail and Information Exchange Process and Commands
Next Topic/Section

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