Review for gContactSync by Wolfman7000
Rated 5 out of 5 stars
Given the negative ratings lately I was a bit sceptic first, but the addon works perfect for me. Syncing works without a flaw, I even played around, deleted and reopened address folders without any data loss.
Summary: I recommend this add on, works fine for me with Thunderbird 11.0
To create your own collections, you must have a Mozilla Add-ons account.