Hello, I apologise if this subject has already been discussed somewhere but I haven't been able to find anything that specifically answers my question. I run Thunderbird on two desktop systems running Windows 7 Professional and a laptop running Windows 10 Home. The desktop systems are running Thunderbird 115.5.1 (32-bit) and the laptop 139.0.2 (64-bit). I use a file synchronisation program to keep my data on all three systems in sync, which also acts as a backup. I also use it to back up my main desktop system to a portable hard drive. I should like to know if it is possible to include Thunderbird data in the synchronisation process, specifically mail messages in various folders (e.g. Sent, Read - including subfolders, Deleted etc.), Address books and Calendar data. I have successfully transferred the message files and their .msf companions. The sync software detects and updates changed files and this seems to work smoothly but I haven't been able to do this with Calendar data or Address Books. As far as I can see this can only be done by exporting the data to iCalendar or csv files then importing to the other systems which is obviously not convenient for something that I am doing on a frequent, regular, basis. A final problem I have encountered relates to message filters. I have not been able to find any way to copy these to the other systems. Copying msgFilterRules.dat doesn't work and I can't find any way to export the filter data. I should be most grateful for any assistance you can offer. Regards, M. J. Thompson.