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-The Hash Convention For Mail System Status Codes (HCMSSC)
-D. J. Bernstein, djb@pobox.com
-19970201
-
-
-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:
-
- <mail-loop@silverton.berkeley.edu>:
- 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:
-
- <foo@heaven.af.mil>:
- 127.3.4.5 does not like recipient.
- Remote host said: 550 <foo>... User unknown (#5.1.1)
-
-
-3. Security considerations
-
- Don't take drastic action upon seeing "(#"; it might not be HCMSSC.