I use Thunderbird 38.5.1 for Linux. I run a well-proven system of filters and virtual folders to organize my mail on my desktop. The filters are actually many (order of 300) and the virtual folders are about 20. This arrangement worked seamlessly until I left for a 10-day journey without tending to email. No-one can have played around with the computer in the meanwhile. As I returned I noticed the following irregularities: The virtual folder that, for example, contained the mail received today (rule 'age in days is 0'), actually contained the mail received on the day of the last check before leaving and on the day I came back. Interestingly, the post sent on the days while I was away is not there. Ever since the folder has then been keeping on stacking the post received each day. Example: in my 'today' folder I have the mail of 12 February (last check before departure) and of every day after 22 February (day of return). The above applies to other folders such as the 'yesterday' folder. There is still see the mail of 11 February (the yesterday of then) and all the mail from 21 February onwards (the yesterday of my return date). I haven't checked all other virtual folders carefully but the difference is certainly visible in these where a time rule applies and is sufficient reason for concern. Basically the content of the folder has not been refreshed any longer. I did cross-check the directions contained VirtualFolders.dat with backup copies of it that I had, and there is no sign of corruption or incorrect syntax in those files. No avail either as I manually ask to update the content of these folders (via the property dialogue). Then, the second concomitant issue occurs at point of downloading my mail from a web account (POP-mode). Then the filters used to redirect the messages to appropriate (non-virtual) folders seamlessly. Now, every now and again, I get a dialogue boxes "The RETR command did not succeed. Error retrieving a message. Mail server pop.whatever.com responded: problem retrieving message." -- then I hit the download button and it goes on for another while until... "The messages could not be filtered to folder '...' because adding a message to it failed. Verify that the folder is displaying properly or try to repair it from the folder properties." -- here I check the named folder and the filters that route into it, but there seems to be nothing to be repaired. Of course, it can be that the problem occurred right the day before departure, but not that I can recall. My guess as a dismayed user is that something went wrong with routing and clock keeping. Look forward to reading your suggestions to fix this. Any welcome solution should preserve the current arrangement of filters and virtual folders -- let's leave unwelcome solution as a last resort. Thanks in advance.