I checked my webmail server, which contained a lot of intray items I had read using my Thunderbird client. I did retain some intray items for further review or response, on the client. When I deleted intray items on the server, then emptied trash, it also deleted everything in my client intray !! How do I prevent this from ever happening again? Some of the lost message content cannot be re-sent to me.

I don't see any reason whatsoever to delete items on my computer when I choose to remove them from the much more public mailserver ?!?!