Review for CardBook by Marco T.
Rated 5 out of 5 stars
Address autocompletion works much better now, at least in Mac OSX, as it puts the most used contacts first when you compose a new mail and start filling out the recipients names.
This alone is worth 5 stars in my humble opinion.
The other features (I need to use) also seem to work as expected.
Works like a charm when connected to Mac OSX Server address book service, which is a VCard service.
If you are on a mac, I'm sure you'll find this add-on to be "the missing Thunderbird address book" that will fill an important gap compared to other clients.
Please note that all of the above is my humble opinion.
To create your own collections, you must have a Mozilla Add-ons account.