Thunderbird doesn't run at the server level, so it cannot do that.

The easiest method is to sync Google Contacts or outlook.com contacts, with or without an add-on, but there is also another method:

https://addons.thunderbird.net/en-US/thunderbird/addon/addressbooks-synchronizer/

Thanks for the replies. Again, sfhowes, I don't want to sync with other email clients, I don't use them. ***Update: I saw that "sync" tool you linked, however I would like to see Mozilla offer this, not a 3rd party.

David, I don't believe that there isn't a way to do this, with all due respect. Thunderbird connects to customer's servers all day, emails sync via imap, and apps and all sorts of other programs sync data all the time. Maybe Mozilla hasn't done the coding, but I suspect it is not impossible.

I have some programming knowledge (granted, I haven't written code for an email client and don't know the nuances of email clients), but it seems a bit of code could easily image or otherwise monitor address book changes and then sync those changes with all other devices via imap or some other similar way. An invisible "email" with a self installing address book update code or some other similar method shouldn't be that hard to figure out, triggered by an update in the address book.

Since Mozilla is all about security and privacy etc, customer's should be able to opt in or out of this as they see fit. I've looked up add ons/extensions and some offer such a service. I just don't trust them; I'd rather Mozilla create that. If they can sync address books, why can't Thunderbird? I'd bet Elon's team could work this out in an hour. Just my opinion and 2 cents, not trying to be argumentative, but I just can't accept that this concept is impossible.

Thanks for the replies. Again, sfhowes, I don't want to sync with other email clients, I don't use them. ***Update: I saw that "sync" tool you linked, however I would like to see Mozilla offer this, not a 3rd party.

Syncing with Google, outlook.com or any other service that offers CardDAV doesn't require other email clients. The service simply provides a central source with which other TB setups can sync.

Syncing of address books and other TB settings is planned (like Firefox Sync) in this year's major release, TB 115, due in the summer of 2023.

Sfhowes:

Thanks for the info. I guess I'll wait for the update and do it manually via flash drive until then. Reference google, outlook CardDAV, I just don't trust them with my, my customer's & friends and family emails.

Thanks for the info, very good news!

I realize this is a bit late, but if you are still looking for a solution... I found a way that works for me. I have a desktop computer and a laptop computer, both running Linux. I copied the 'abook.sqlite' file from my Thunderbird profile into my Dropbox directory. Then deleted the file from the profile, and created a soft link to the Dropbox file. Repeat on the second computer. This is definitely a hack and has the obvious shortcoming that a Thunderbird update might overwrite the soft link. There could be other unexpected consequences as well. Use at your own risk.