authentication
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... AUTHORIZATION state. The client must
now identify and authenticate itself to the POP3 server. Two
possible mechanisms for doing this are described in this document,
...
... command is described later in this document.
To authenticate using the USER and PASS command combination, the
...
... client
may issue either the PASS command to complete the authentication, or
the QUIT command to terminate the POP3 ...
... ERR") to the USER
command, then the client may either issue a new authentication
command or may issue the QUIT command.
...
... Once the POP3 server has determined through the use of any
authentication command that the client should be given access to the
appropriate maildrop, the POP3 ...
... connection, the client
may either issue a new authentication command and start again, or the
client ...
...
An alternate method of authentication is required which
provides for both origin authentication and replay
protection ...
... method of authentication is required which
provides for both origin authentication and replay
protection, but which does not involve sending a password
...