(Contribution by user David Taber - thanks - slightly adapted by Marco Zanon)

Google-4-TbSync... if you used to be a gContactSync user

gContactSync is gone, so it's time to move on. Google-4-TbSync is quite a bit different, and there are some one-time transition issues in setting it up. The docs are pretty good for that... but there are some things you'll need to get used to.

But before you do anything, you must backup your data. Do it both from Google and Thunderbird... although the Google side is going to dominate.

Now of course, gContactSync has been offline for several Thunderbird versions, and the data on both sides of the sync has probably evolved. Guess what: you can't just sync the updates, you must start a new, fresh addressbook in Thunderbird.

Don't yell at me, I didn't do it.

So what this means is you have to go through your Thunderbird addressbook and manually apply the changes to the Google contacts. I did this by editing the Google contacts in Excel, but you may have a better approach. One way or the other, Google is the undisputed master.

So you've spent the hours and days making the updates to Google

And now what do you do? You make an archival copy of the Google CSV, and just save it. Then you delete all the contacts in Google. And then you import your edited, all-up-to-date spreadsheet you've been working on back into Google.

Once the Google contacts are all in place, you create a new addressbook in Thunderbird and sync it.

So now you have contacts in both, all aligned.

But if there weren't any surprises, what kind of fun would that be?

0. You really want to read up on the TbSync Account Manager tool before you set things up. The docs for this are in the TbSync GitHub, not the Google-4-TbSync one. Early on, you probably want to keep sync as Read-only mode... uncheck that option only when you feel confident.
1. All the Google labels will come over as Thunderbird mailing lists. But only contacts that actually have an email address will populate those lists (the contacts always come over, but the lists may be sparse or even barren)... unless you check the Use fake email addresses option, which allows email-less contacts to populate Thunderbird mailing lists.
2. To perform a fast synchronization, just click on the TbSync icon on the main Thunderbird toolbar (which can be added if you don't already have it), then select the desired account and click Synchronize now.
3. If you go to the Account Setting tab of that same tool, you'll see some interesting options. Which you can't select. You have to disable synching to change them, and when you disable synching, your Thunderbird addressbook will disappear! So always sync before you disable it!
4. But also on that tab is a Check connection button, and when you push it you'll get a result with data about your contacts and lists. Now, the contact number will always be right (for what Google holds), while the list number will count the system groups in your Google account ("family", "friends", "myContacts", etc.) only if you check the Include system contact groups option.
5. And another thing. If you look at the number of contacts in Google, it may be less than the number in your Thunderbird addressbook. Why? Because Thunderbird counts its mailing lists as contacts (even if those lists aren't populated). So: Thunderbird contacts - Thunderbird mailing lists = Google contacts.

Last updated: 25th July 2021