Your filters will be trying to move mail to folders that no longer logically exist. I would suggest opening the messagefilterrules.dat file in notepad and see if you can change any references to gmail to googlemail. Note you must save it in notepad using the sub file type unicode, not ansi.

The folders exist. They're being read off of Gmail's server.

actionValue="imap://xxxxxxx%40gmail.com@imap.googlemail.com/[Gmail]/extra" As you can see there is a [Gmail] in the line.

There would normally be three, but I'm obsessive.

The, one that is important is @imap.googlemail.com, which has been globally changed from @imap.gmail.com quite some time ago.

And I may have a final clue. I emptied out the Inbox, leaving a half dozen messages (down from 2000), and then refreshed the msgfilterrules.dat and manually ran the filters. No error messages.

I then waited for a mail run, made sure any disabled filters were corrected and enabled, and manually ran the filters. No error messages.

I then let a mail run happen on automatic. No error messages. k With the Inbox nearly empty, filtering works as expected.

One workaround is to get caught up on filing email into folders.

The bug has to do with:

1) The volume of the mail in the Inbox (formerly 2080 pieces), or

2) The time it's taking to process the filters; specifically, the time spent checking for the existence of the destination folder before it gives up and concludes the folder is not there.

Never mind my last post. It just broke on one incoming message. The folder is there, but I still got the error message.

I think this is connected to an older bug. I'll see if I can find it.

The number of mail in the folder is going to be an issue for me then, with some 22,000 in the inbox some 8.000 of which are unread. But it is not.

It is not. I apply mail filtering to incoming messages and the Inbox only. I emptied the Inbox by moving all but four of the messages elsewhere, and it still breaks.

It appears to be a bug of some type. The precise description is that a mail run starts, the filter is applied, the filter log shows the message as moved, and then the error message and disabling of the filter rule happens. Upon examination, the message (reported by the filter log as moved) is still in the inbox.

I see a number of possible causes. AS you do not receive any error about the folder being in use. It is unlikely to be an internal Thunderbird process.

I suggest you create an exception in your anti virus for the Thunderbird profile folder and see if it gets better. My guess is it will. You can not write to files that are locked by the anti virus while it is scanning them for a quarter of an hour.

Given you are still using XP your machine is probably slow by modern standards and timing issues will be exaggerated.

Matt said

I see a number of possible causes. AS you do not receive any error about the folder being in use. It is unlikely to be an internal Thunderbird process.

Maybe. I'm thinking that Thunderbird is checking the existence of the folder on the server while trying to filter mail at the same time.

I suggest you create an exception in your anti virus for the Thunderbird profile folder and see if it gets better. My guess is it will. You can not write to files that are locked by the anti virus while it is scanning them for a quarter of an hour.

Done, and no change.

Given you are still using XP your machine is probably slow by modern standards and timing issues will be exaggerated.

Not by much. I have 1.5 gig of RAM and 80 gig of hard drive space (65 gig free, roughly). Thunderbird is taking up 300K of RAM as I type this against a swap file of 1 gig. Task Manager is showing less than 10 percent utilization with Thunderbird open and filtering complete.

@Matt I'm a bit unsure how moving to another IMAP-folder works.

1. Do TB tell server to move the message and then synchronize the folders? OR
2. Do TB move it to the local view of that folder and then synchronize and upload it to server? OR
3. Do TB move it to local view of folder and tell server to do the same?