Clearly. https://support.mozilla.org/en-US/questions/1562223 Personally I would think using carddav from the account setup is the easiest. But outlook uses have been trained to think inside the Outlook app box. Further Microsoft still insist of proprietary data interchange so web based contact is not simple. It is for those that use Yahoo, Google and any of the other standards based providers in the market it is as simple as adding the mail account.