RFC 630 (rfc630) - Page 2 of 3

FTP error code usage for more reliable mail service

RFC 630          FTP Error Code Usage for Mail Service        April 1974


                     NEW DEFINITIONS FOR TENEX USE

    The following changes will be installed at TENEX sites over the next
couple of months.

FTP SERVER

    The TENEX FTP server will continue to use 452 and 454 as specified
for the MLFL command.

    For MAIL and MLFL, it will send the other codes as follows:

450 Permanent failures due to the user addressed in the Mail or MLFL
    command.

    Examples:  No such user; No mailbox for that user; Can't access file
    (because net users can't write in that mailbox).

451 Permanent failures due to the message itself.

    Example:  Line sent over TELNET connection is too long (MAIL command
    only).

453 Temporary failures

    Examples:  TELNET connection unexpectedly closed;  Mailbox busy;
    Unexpected local errors (such as failure to create scratch file).

MAILING PROCESSES

    TENEX mailing processes currently interpret all the codes 450-454 as
meaning permanent failure.  They will be changed to interpret 452, 453,
and 454 as temporary while leaving 450 and 451 permanent.


                   COMPATIBILITY WITH NON-TENEX SITES

    These interpretations should not adversely affect the interaction of
TENEX and non-TENEX mail processes, since we are simply changing from
one arbitrary set of interpretations to another.  Moreover:

--Our interpretation of 450-451 as permanent and 452-454 as temporary is
consistent with their original meanings.

--Our new choice of what codes to use for what failure is no farther
from the original meanings than our old choice was, and conveys more
information.




Sussman