Select an address book in the left pane of Address Book, then select (so they are highlighted) contacts in the right pane, then drag them to the left pane and drop them on the list icon.

Thanks. That's what I needed to know.

Thanks a bunch!

Hello there Karen corrick. We have read your message We try to help you.

your letter informs us that there is a complaint about use with your address book in Thunderbird.

The use of this program can be used in several ways let's assume that you quickly add a contact in your address book.

At the time of this contact with the email address To add, a contact sheet may appear at that time and also at the same time there may also be no contact sheet that will appear.

With the quick addition of the contact and email address, a contact sheet will clearly appear, if not then you will indeed have to enter the contacts manually in the indicated sublists that exist in and for this topic.

https://support.mozilla.org/en-US/kb/how-create-and-use-mailing-lists-thunderbird

Greetings Firefox volunteer

I can't work out how to do what you suggest. If I select a list in the left pane, only the contacts in that list are visible in the right pane. What I want to do is add a contact who already exists into a particular already existing list. Please, can we go back to the system we had before. It was easy to add or remove contacts from a list

I found that if I highlighted the list to be updated, then click the 3 dots on the left of the entry, there is a properties tab. Click that and there is a window where you can add new entries. It looks like the contact must exist in your address book before it can be added to the list.

As well as @runtewerx's method above (thanks!), if the contact is already in your address book, you can go into there click on address book or a list that it's in on the LH pane, then drag the contact from the RH pane into the list you want in the LH pane. This works for T-bird in Windows as well. HTH

I found similar, but simpler (?!) answer, to the above.

Firstly find the list name where you want to add the contact.

Right click the list name (or click the three dots against the list) - click Properties and a form will pop up allowing you to enter the person's details, and click OK and you are done!

(If the person already exisits on a mailing list, it will probably populate as you are typing in the name).