[Extra] IMAP4rev2, SEARCH CHARSET

Arnt Gulbrandsen <arnt@gulbrandsen.priv.no> Thu, 07 November 2019 10:39 UTC

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From: Arnt Gulbrandsen <arnt@gulbrandsen.priv.no>
To: extra@ietf.org
Date: Thu, 7 Nov 2019 11:39:03 +0100
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Subject: [Extra] IMAP4rev2, SEARCH CHARSET
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Hi,

SEARCH CHARSET is a bit ungood now.

IMAP4rev1 used ASCII generally, and the CHARSET specification could be used 
to use something else in a search key. However, IMAP4rev2 now uses UTF-8 
generally (see section 4.3.1), and so CHARSET becomes rather odd.

I suggest obsoleting CHARSET and telling clients to use UTF-8 for searches. 
Suggested text (for 6.4.4):

"In IMAP4rev1, the client could specify the character encoding of non-ASCII 
search keys using SEARCH CHARSET. In IMAP4rev2, the client uses UTF-8 for 
all search keys, and for this reason CHARSET is now obsolete."

My question is: Obsolete CHARSET and say clients MUST NOT use it, or 
obsolete it and say that servers MUST support CHARSET UTF-8 and MAY support 
others?

Arnt