Hello- I just installed Thunderbird Version 52.1.1 (x86). I have about 800 messages I want to send to trash folder. I know how to delete them one by one. Do you know any quick way I can delete them faster than that? It would be nice to be able to press a few keys, etc. and send them to the trash folder all at once.

 I am asking this because  I "sign out"  the account first and then close Thunderbird to where no one will see any new messages until I log back in again.  I hope that makes sense.