I recently added a key in Thunderbird 'Config Editor'. This key is given a null value. It is supposed to hide email client info in outgoing mail headers.
It goes something like general.override. I do not remember the exact key name. Adding this key has somehow removed the filter box that is available in Thunderbird, on the top right, below 'search mails' box.
I was checking this option today and selected Reset. Since then on, this key is nowhere to be found.
Can someone suggest how to remove the key and bring back the filter mail option?