Network Working Group D. Bernstein
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Category: Informational 13 August 1996
The Hash Convention For Mail System Status Codes (HCMSSC)
Status of this memo
This memo provides information for the Internet community. This memo
does not specify an Internet standard of any kind. Distribution of
this memo is unlimited.
1. Introduction
RFC 1893 defines codes for mail delivery failures. For example,
code 5.1.1 means that the specified mailbox does not exist.
The qmail package sprays these codes all over the place, by adding a
code to the text of every error message, preceded by a hash mark and
surrounded by parentheses. It avoids using hash marks elsewhere.
2. Examples
Here is a typical HCMSSC SMTP error message:
421 load average too high, please come back later (#4.3.2)
Here is part of a typical HCMSSC bounce message:
:
This is looping; it already has my Delivered-To line. (#5.7.1)
But qmail doesn't use HCMSSC when it repeats another MTA's error
message:
:
127.3.4.5 does not like recipient.
Remote host said: 550 ... User unknown (#5.1.1)
3. Security considerations
Don't take drastic action upon seeing "(#"; it might not be HCMSSC.
Author's address
D. J. Bernstein
EMail: djb@pobox.com
Bernstein [Page 1]