4.1.4 CardBook

CardBook is an awesome complete and well-tested Thunderbird extension implementing many features missing from the default Thunderbird address book (that will actually get reworked soon).

Although, there will be a glitch against Thunderbird v68 if you use this thunderbird user.js.
You'll have to relax network.cookie.cookieBehavior from 2 to 1.

For further information, see this page.

This has been setup here for instance.