Recently-APPENDed messages not showing up as RECENT responses after NOOP

[John J Lee]

On Mon, 4 Sep 2006, Kjetil Torgrim Homme wrote:

> On Sat, 2006-09-02 at 15:48 +0000, John J Lee wrote:
>> The problem occurs when SpamBayes (specifically, sb_imapfilter.py) tries
>> to add an X-Spambayes-Classification header to emails it has classified,
>> in order to record whether it thought the mail was spam or not.  It does
>> that by creating a new message with the added header, then deleting the
>> old message (if there's a better way, I'd be grateful to learn about it).
>
> oh yes, please use flags!  Cyrus supports arbitrarily chosen flags by
> clients, see PERMANENTFLAGS.  (of course, other IMAP servers aren't as
> advanced, so you may want to keep this wasteful APPEND/STORE/EXPUNGE
> hack around for those.)

Aha!  Thanks.  If anybody has any pointers to sample client code, I'd be 
grateful.

Still, the old-style SpamBayes code should also be fixed for 
non-flags-capable servers -- see below re Courier (and it'll take me a 
while to get around to attempting to implement the flags-based version).


>> As soon as SpamBayes creates the new message, it tries to find the new
>> message's UID.  To do that, it first looks for a RECENT response.  If it
>> doesn't have one it its buffer, it sends a NOOP command.
>
> you can't trust RECENT, if a different client is connected, your
> SpamBayes client may not be told about the message, since only one
> client will be notified.
>
>> If that doesn't
>> result in a RECENT response, it keeps polling, issuing NOOP commands up to
>> 100 times (it doesn't sleep() between each poll).  If that fails, it dies
>> horribly :-/
>
> this is really unnecessary.  when the APPEND is done, SpamBayes can
> simply do a SEARCH to find the message with the Message-ID and fetch its
> UID.

OK, I was mistaken about the reason is does this loop.  The loop is there 
not to find the UID (the code does indeed do a SEARCH for that), but 
rather to wait until the new message is available, prior to SEARCHing for 
the UID.

Does that make more sense, or is there still a better way to do it?


>> 2. Does this reveal a bug in the Cyrus implementation?
>
> hard to tell.  is it the only client?

I don't understand your question.  Is SpamBayes the only client of Cyrus? 
No.  Did you mean "is Cyrus the only server that fails with this client 
code"?  Seems not: somebody reported Courier failing intermittently too.


John