Since ver 115 Thunderbird opens links in emails in a new Firefox window. How to change it so that it opens the link in an already open Firefox window but in a new Tab. If Firefox is not already open it will open Firefox in the previously closed window but within a new tab in that window. However, if Firefox is already open with multiple tabs in the window then Thunderbird opens the link in a new window instead of a tab in the existing window. I am pretty sure it never did that prior to ver 115.