This works in TB 91:

https://addons.thunderbird.net/en-us/thunderbird/addon/deselect-on-delete-tb78/

https://support.mozilla.org/en-US/kb/installing-addon-thunderbird

I followed the procedure to install this. I checked it under "extensions", it's installed and enabled. I restarted Thunderbird, opened an eMail, then with it open I used the button to Delete It. It got deleted and the next eMailed automatically opened.

This is the same problem I had and asked about.

I tested the add-on before suggesting it. When messages are opened in the Message Pane, deleting a message makes the pane blank, i.e. no other message is opened. I don't know why it doesn't work for you.

I have the Thunderbird settings set to open an eMail in it's own window. In that window, when I click on the delete button to delete that eMail, that eMail gets deleted, then the next eMail opens in that same window.

I hope that this can get fixed.

- Alan

I can confirm that the add-on doesn't deselect after a message is deleted from a separate window. It does work for messages opened in the Message Pane or a tab.

I suggest you contact the add-on author to find out if this is a bug or a restriction imposed by TB's window management.