I recently created templates so I can create different address books for my Thunderbird and Zimbra address. All I did was export my address books as a .CSV file. I then cleared any contents I had in the spreadsheet. Now, I can fill in my info and i have the proper headers that will be brought into brother Thunderbird and Zimbra. This is a great way to move around your address book.
If you use two different email clients and you don’t want to recreate your address book in one on the other system, you can export the file and them simply import that file. The template is good if you are starting from scratch or if you have a long list of new emails for a certain group, you can just copy and paste that information into the template and then import it. I have the two templates already created and you can view them below. Enjoy!