Re: The IMAP APPENDLIMIT Extension

Hi Pete,

Thanks for your review comments. 

Please find my comments inline. 

Regards,
Jay

-----Original Message-----
From: Pete Maclean [mailto:[email protected]] 
Sent: Saturday, January 03, 2015 8:11 AM
To: Jayantheesh S B; '[email protected]'
Subject: Re: [imapext] The IMAP APPENDLIMIT Extension

Jay,

I have not said anything on APPENDLIMIT before but, reading your latest draft now, there are a few things I wonder about.  I don't think any of these necessarily requires any changes to the draft but some may merit additional consideration.

In section 5 you make reference to "the server's fixed maximum mail upload size".  What is the intended scope of said fixedness.  Should a client assume that a maximum upload size obtained in one session applies in a later session?  I think it should not.  Hardware or other changes at the server could surely lead to a maximum upload size changing over time.

[Jay] Upload size obtained using SELECT/EXAMINE always overrides the CAPABILITY response. So, maximum upload size obtained in one session does not apply for another session.

How should a client behave if it obtains a maximum upload size for a given mailbox in a LIST command and then later in the same session it does a SELECT/EXAMINE for the same mailbox that quotes a different maximum upload size?  For that matter, is it valid for a server to return different maximum upload sizes in CAPABILITY responses within a single session?  In cases where a maximum upload size is dependent on a quota, it could make sense for these things to happen.

Surely it would be very valuable to include in this extension a means for a server to indicate that it does not accept APPENDs at all.  For IMAP servers fronting email archives, it is entirely reasonable for APPENDs to be unsupported.  In other cases, it seems reasonable for APPENDs to be disallowed for certain mailboxes (as, for example, in a proxy situation or when a mailbox reaches maximum capacity).  An easy way to deal with this would perhaps be to change the syntax to allow an append limit of 0 with the meaning, not that zero-length messages may be APPENDed (something that my checks show that many servers disallow anyway), but that APPENDs are not allowed period.  This could avoid a lot of trouble, I believe.

[Jay] This is the good idea. I will change the next version of the draft to accept the APPENDLIMIT=0, indicates the server will not accept any APPEND command due to size restriction.

Pete Maclean

At 05:12 PM 12/19/2014, Jayantheesh S B wrote:
>Hi All,
>
>Please find the next version of the draft attached with all the review 
>comments addressed.
>
>If you have any comments/suggestions in the attached version, kindly share it.
>
>Regards,
>Jay
>
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