Re: [MORG] WGLC on draft-ietf-morg-inthread-00

[Mark Crispin <markrcrispin at panda.com>]

On Fri, 27 Mar 2009, Curtis King wrote:
> I did a check on my server to see what extensions are being used by clients 
> and there only seems to-be 10 extensions in use by the most common imap 
> clients.

I am not particularly surprised.

> Clients: Apple Mail, Thunderbird, Mobile Mail, Outlook and php imap client. 
> Mark your client is missing but I'm sure you can add any missing extensions 
> to the list :-)

I think that Pine/Alpine remains a fairly important client!  ;-)

I'm surprised by your report about PHP-IMAP, since it uses the same 
internal engine used by Pine, Alpine, UW imapd, and Panda imapd.  Maybe 
PHP-IMAP doesn't offer a sort capability.

So, with that said...

> Extensions: STARTTLS, AUTH=, LOGINDISABLED, UIDPLUS, LITERAL+, NAMESPACE, 
> IDLE, ACL, UNSELECT and QUOTA.

Of the listed extensions:

Pine/Alpine uses STARTTLS, AUTH=, LOGINDISABLED, NAMESPACE, and UNSELECT.

Pine/Alpine does not use UIDPLUS, LITERAL+, or IDLE, but these are all 
implemented in UW/Panda imapd.  I do not dispute their value, other than 
disputing the claim that LITERAL+ is a satisfactory alternative to 
MULTIAPPEND.

Pine/Alpine does not use ACL and QUOTA, and these are not implemented in 
UW/Panda imapd.  I continue to believe that both extensions are broken by 
design, but I don't care to continue that debate.

In addition to the above named extensions:

Pine/Alpine uses SCAN and THREAD=.  A major advertised feature depends 
upon these.  Performance is miserable without it.

Pine/Alpine uses MULTIAPPEND for cross-mailstore copies, and performance 
is miserable without it.  LITERAL+ does not address the underlying cause 
of the problem.  Nonetheless, the biggest use of MULTIAPPEND is in 
external administrative programs to move users between servers; I can't 
imagine IMAP being used for that purpose without MULTIAPPEND.

Pine/Alpine also use LOGIN-REFERRALS and MAILBOX-REFERRALS, but I doubt 
that any tears would be shed by their demise.  AFAIK, Cyrus was the only 
server that implemented it.

I implemented several other extensions in UW/Panda imapd mostly because 
they were trivial, low-hanging fruit; but I have no illusions that any of 
these are of any real value.

> I'm sure there are some more clients which use a few more extensions, but 
> that still means ~16 extensions we (Isode) have implemented are not being 
> used. Not a very good ratio. Yet, here we are planning on adding more.

I agree.  I have largely kept quiet here because I think that the entire 
exercise is more or less harmless, albeit silly.  As I was responsible for 
similiar silliness in my youth (my very first RFC was the TELNET Logout 
option), indulgent toleration seems to be the best policy.

-- Mark --

http://panda.com/mrc
Democracy is two wolves and a sheep deciding what to eat for lunch.
Liberty is a well-armed sheep contesting the vote.