About this Add-on
This is the Thunderbird fork now that the latest Firefox version (https://addons.mozilla.org/en-GB/firefox/addon/url-link/) has been converted to WebExtensions — please report any issues to me or via a bug on GitHub.
Note that as of Thunderbird 60, the preferences dialogue is only available via the Tools / Add-on Preferences main menu.
For emails, it reconnects links in emails which have been broken across several lines, and also replaces spaces with the URL character code %20 so that you may follow emailed network 'file:' links (which it auto-detects from Windows "X:" or \\servdir references).
For web pages, it also allows you to select textual links/URLs in web pages or edit boxes, and follow them as if they were real links. It will also let you use actual links, and analyses mailto: links as well.
There are currently more translations than I care to keep listing here (thanks to the guys at http://www.babelzilla.org/)! Unfortunately, Babelzilla has retired due to the new format of Firefox add-ons. If you would like to provide new translations, or fix existing ones, please email me, add them to a feature-request issue on GitHub, or add them in a GitHub fork for me to pull in.
URL Link has a preferences dialogue allowing customisation of the 'not a proper URL' sub-menu which converts, e.g., "sometext" to "www.sometext.com", so that locale-specific conversions can be added (like 'www.*.co.uk').
Nicknames can be applied to the entries (such that the nickname appears in the menu, not the conversion string) by using a bar '|', e.g.:
It also allows separators to be added to the custom menu by using entries made up of hyphens, e.g. "--".
Hold down Shift when opening a link in the current window to instead open in a new window.
Either hold down Control when opening a link, or add |p to the end of a custom menu entry to make that entry always open in a private window.
You can also set up custom search and replace strings (e.g., convert Windows driver letter to some file:///mnt/smb/ path for Linux users).
If you have problems with file: or network (\\server\share) links, especially in Thunderbird emails, see the following page:
PLEASE if you have a problem, or wish for a new feature, contact me directly or via GitHub, as I rarely remember to visit this page to check on the comments, so it may take me a while to respond!