My wife and I are both using Thunderbird 102.9 on Windows 10, with the emails stored in "maildir" format. (One file per message.) Last night when I was backing up the Thunderbird profile folder on her laptop to another drive, I noticed that a huge number of files had been modified, and they mostly had the same modification date and time (give or take a few minutes.) (I use FreeFileSync to copy the changed files to the other drive, but that's probably not significant.) After a day's usage, I would expect a couple of hundred megabytes of data to need copying, but in this case, it was well over a gigabyte. The files that were being updated ranged from a few days older to a year or two older than the files which were being copied over them. Running her Thunderbird installation today, all seems normal; the email "received" and "date" times seem normal, and it looks like the emails themselves aren't corrupted. I'm wondering if there's any function within Thunderbird which would cause these file dates to be modified en masse in this way? (Or perhaps it's a Windows 10 thing... but as far as I know, no file date modification utilities were in use, nor is there any malware on our systems. (I think Malwarebytes Pro would be throwing up warnings all over the place if this was the case, and we scan daily.) Any suggestions would be gratefully received. Kind regards, Roger V.