I want to import my address book from my xfinity internet account to my new mozilla thunderbird account. I had this data in thunderbird on my old computer, but it died and this is a new computer.
Using the new computer, sign into the Comcast account and open the address book, and in the left pane click on "Address book" again. To the right click on the "hamburger" icon and you will see the option to Export it. Export it to your desktop on the new computer. It will be there as a .csv file, and you can then import it into Thunderbird.