RFC 1204 (rfc1204) - Page 2 of 6
Message Posting Protocol (MPP)
Alternative Format: Original Text Document
RFC 1204 MPP February 1991
354 Enter mail, end with .
451 Local error encountered.
500 Command unrecognized.
501 Argument syntax error.
503 Illegal command sequence.
530 Authentication Failure.
550 Error.
2.3. Command and Reply Descriptions
USER
The USER command informs the message posting server about the
username of the user trying to submit mail to the network. The
required argument for the USER command is a string specifying
the message sender's username.
The USER command can only be used under three conditions:
- when the session with the message posting server has just
started;
- right after a message text (terminated by the "."
sequence) has been successfully submitted to the message
posting server;
- right after a USER command that gets the reply code 501.
List of possible reply codes for the USER command:
- 250 The username of the message sender has been accepted.
- 451 Internal error has occurred in the message posting
server.
- 501 Syntax error detected in the username argument.
- 503 The USER command has been used under an inappropriate
condition (i.e., one that is not specified above).
It is recommended that the message posting server should return
250 even if the username is not recognized by the message
posting server, as long as the username is syntactically
correct. This is an attempt to prevent the message posting
server from releasing too much information about the user
database. Client should not be able to test the existence of a
certain username.
Yeh & Lee