Subject: [Extra] IMAP I18NLEVEL

From: Ken Murchison <[email-masked]>
Date: Mon, 28 Jan 2019 17:02:25 -0500

All,

Some of us at FastMail have been discussing implementing RFC 5255, 
namely the I18NLEVEL extensions, in the Cyrus IMAP server and we are 
wondering if any clients support and use them.

-- 
Ken Murchison
Cyrus Development Team
FastMail US LLC

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From: "John Levine" <[email-masked]>
Date: 28 Jan 2019 21:30:14 -0500

>wondering if any clients support and use them.

Why 5255 rather than RFC 6855?  It is my impression that in practice
the UTF8 support in 6855 made the older stuff obsolete.

Since Chris Newman was an author of both, he's the obvious person to
ask for more info.

---

From: "Chris Newman" <[email-masked]>
Date: Mon, 28 Jan 2019 23:13:57 -0800

> Since Chris Newman was an author of both, he's the obvious person to

The two standards are orthogonal.

I have most of an implementation of RFC 5255 on our server, but don't 
advertise it. The issue is we implemented an earlier draft of the 
specification which used a UCA-based comparator. I don't have time to 
implement/test i;unicode-casemap and consider that algorithm inferior to 
UCA. I'd be inclined to fix and advertise our implementation if a 
UCA-based comparator was registered and allowed as an alternative to 
i;unicode-casemap. But use of i;unicode-casemap was easier to get 
published at the time this was done. This could probably be fixed with a 
relatively short specification but I can't justify the time to write it. 
In the meantime; I'd recommend using JMAP for i18n sort since it gets 
that detail right :-)

I have a full implementation of RFC 6855 although I ignored one or two 
of the backwards compatibility MUST/SHOULD rules which were necessary 
from a standards viewpoint and inappropriate from an implementer 
viewpoint :-).

Basically RFC 5255 handles sorting and error text localization -- a nice 
to have feature but default behavior in IMAP is good enough. RFC 6855 
handles UTF-8 email headers and mailbox names -- as EAI deploys, you'll 
start getting customer complaints if you don't implement this. So given 
limited time, I'd recommend doing RFC 6855 first.

		- Chris

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From: Arnt Gulbrandsen <[email-masked]>
Date: Tue, 29 Jan 2019 22:31:00 +0100

> Some of us at FastMail have been discussing implementing RFC 
> 5255, namely the I18NLEVEL extensions, in the Cyrus IMAP server 
> and we are wondering if any clients support and use them.

I did the last drafts of that, when Chris was distracted. Noone's sent me 
mail about it until now.

This might of course mean that noone's had problems understanding the 
prose, noone found typoxs, and noone needed help finding interop partners. 
But I fear that in this case, it's more likely to mean that the number of 
implementers approximates zero. Particularly since noone said they wanted 
to implement before publication; I only finished the document since doing 
that was simpler than getting it removed from the WG charter.

Arnt