BrowseInTab for Thunderbird
Open and browse any link in a Thunderbird content tab. Links are followed within the tab and back/forward navigation is supported.
Thunderbird 68 - BrowseInTab v1.7
Back/forward navigation. Via context menu, alt left/right arrow key, or standard mouse buttons.
Open a link using a context menu or configure loading in a tab on link click instead of opening in the default browser.
Options to set the maximum number of content tabs (not exposed in core Tb), or open a tab and focus it immediately are also found in Options/Preferences in Add-ons Manager.
Option to force content tab link or button clicks that would open in a tab (target="_blank") to open in the current tab.
Option to use the Firefox Compatibility user agent string for link loads only.
Option to add Content-Base header url link (with custom label) to Compose Forward Inline messages.
NOTE: Thunderbird is not designed to be a browser. The content tab has a read-only urlbar, no history in the back/forward buttons, and no session history for tabs (only the current url in the tab is restored). There is not fine grained control as found in, for example, the Firefox Privacy and Security preferences. It is recommended that an ad blocker like uBlock be used for an extra layer of privacy/security.
Comments, Questions, and Bugs: