RFC 2919, "List-Id: A Structured Field and Namespace for the Identification of Mailing Lists", March 2001Source of RFC: IETF - NON WORKING GROUP
Area Assignment: app
Errata ID: 361
Publication Format(s) : TEXT
Reported By: Trish Lynch
Date Reported: 2002-08-08
Rejected by: Alexey Melnikov
Date Rejected: 2010-05-11
Section 3 says:
The syntax of the List-Id header follows: list-id-header = "List-ID:" [phrase] "<" list-id ">" CRLF
It should say:
The syntax of the List-Id header follows: list-id-header = "List-Id:" [phrase] "<" list-id ">" CRLF
In order to bring it in line with the examples, and with common usage (by
the RFC, the List-ID is correct) most mail readers use the example and
do not consider the LHS case insensitive, since the RFC says:
The list header fields are subject to the encoding and character restrictions for mail headers as described in [RFC822].
RFC822, while it says that most headers are character insensitive, does
not mandate that, and RFC 2919 only mandates that the List-Id: header is
subject to *encoding* and *character restrictions*, and does not say it
needs to adhere to case insensitivity.
Therefore, the proposed change above will bring things more in line with common
Header field names are case insensitive per use of string literals from RFC 2234.