User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.8.1.3) Gecko/20070309 Firefox/2.0.0.3 Build Identifier: version 2.0.0.0 (20070326) There are 2 filters set in Thunderbird. One filter is set under filter rules as "For incoming messages that: Match any of the following: 'From' 'Contains' 'jon@doe.com' move email message to a folder called jon@doe.com". The second filter is set as "For incoming messages that: Match any of the following: 'Size' 'is greater than' '500' move message to a folder called Big Attachment". The problem comes when I get an email from jon@doe.com that is filtered with the second mentioned filter into the "Big Attachment" folder. When I move the message from jon@doe.com from the "Big Attachment" folder to the "jon@doe.com" folder the message just disappears. Reproducible: Always Steps to Reproduce: 1. Everything is in details section 2. 3.

I've also ran "Compact Folders" from the file menu with no discernible fix.

Sounds "move by filter" version of Bug 380880(already DUPed to fixed Bug 368112)

Agreed. Try a nightly for the fix.