Mail problem interfering with Spamsieve

I am pretty certain this is a Apple Mail problem. However, it’s primary symptom is that SpamSieve appears to stop working, so I thought someone here might have run across this.

Periodically, every few months Mail may decide it needs to resynchronize a bunch of IMAP folders from a FastMail.fm account. I do not know the source of this but it is problematical due to FastMail bandwidth management. For some reason Mail will decide to download 2GB or so out of 7GB of content on the IMAP server. When this happens most often than not, Spamsieve will seem to not be processing messages. When I look at Spamsieve’s console log, it appears no messages are being processed by Spamsieve. However, if I use a Mail menu spamsieve training menu pick, I will see an entry in the log. Additionally, if I select all the offending emails, that is SPAM in my Inbox, and then manually “apply rules” via Mail’s menu, the offending messages will be moved to the appropriate SPAM folder. Any thoughts as to how they are showing up in my Inbox without Spamsieve seeing them?

The most peculiar issue when Mail is in this state is that if I take the offending Mail account offline. The Inbox will continue to be updated with new messages. I’m thinking this is the root cause of the problem. In that if the account is offline, then nothing should be processed. However, if it is offline, I wouldn’t expect that new messages would be displayed.

Any thoughts or suggestions on how to fix?

(I am running Mac OS X 10.6.2. Although, the synchronization problem first showed up under 10.5.x earlier this year. However, the SpamSieve non-processing seems to have only been subsequent to 10.6 .)

Mail needs to download the whole message to send it to SpamSieve. My guess is that if this can’t be done, due to your bandwidth problem, Mail eventually aborts applying the rules and just leaves the message in the inbox.

Sorry for being unclear in my first post. The bandwidth problem is that I have too much from FastMail’s perspective. So it will suck down 30,000 or more messages. Note, these messages are typically not in the Inbox but in other mailboxes such as the one I use for SPAM and would not be processed by SpamSieve. However, it is during such periods that SpamSieve is not getting the messages. I have an 8 core MacPro so there is plenty of available CPU. I’ll post in the Apple forums to see if I get anything there. Thanks.