There is no setting for it; it happens when you press Shift-Delete. There is also an add-on: https://addons.thunderbird.net/en-US/thunderbird/addon/confirmbeforedelete/, but it only works on versions up to 137.

As mentioned above, there is no confirmation dialog for Delete, without an add-on. For Shift+Delete, there is a preference in Config. editor: mail.warn_on_shift_delete. It defaults to true, but is false if you checked the box in the dialog.

Strangely Ed & SF I have had a confirmation delete dialogue forever since I started using Thunderbird decades ago. I stupidly ticked the do not confirm and now no way to recover from that it seems with all this add on stuff. Thankyou for your comments

Strangely Ed & SF I have had a confirmation delete dialogue forever since I started using Thunderbird decades ago. I stupidly ticked the do not confirm and now no way to recover from that it seems with all this add on stuff. Thankyou for your comments

Go to TB menu > Settings > General

- scroll all the way down and click the 'Config editor' button on the right

- click 'Accept the risk and continue' if that appears

- search for mail.warn_on_shift_delete > change the value to false

- a couple of options up, also change the value of mail.warn_on_delete_from_trash to false

Many thanks Ed and SF. Easy fix if one knows stuff as you do. Also thanks for fast response amazing.