Export contacts from Thunderbird to Gmail

Moving my mail life from Thunderbird to Gmail in the browser and the last piece is the address book, several hundred contacts across the Personal and Collected books.

Direct route, or does this go through intermediate formats?

Nearly direct: one export, one import, with the format choice on the Thunderbird side deciding how much hand mapping the Google side asks of you.

1

In Thunderbird open the Address Book and select the Personal Address Book. In modern versions the export lives under the book's own menu or Tools, Export, offering CSV and vCard formats. Choose vCard when your version offers it, Google reads vCard with the least field confusion or Comma Separated with the Unicode variant when names carry accents.

2

Skim Collected Addresses before exporting it at all: it is every address Thunderbird ever auto captured, mostly one time senders and importing it wholesale plants years of noise in Gmail's autocomplete. Export it separately if at all, or cherry pick its few keepers into Personal first and export once.

3

At contacts.google.com click Import, feed it the file. vCard imports map themselves, CSV imports get filed under a dated Imported label either way, giving you a review pen before the contacts mingle.

4

Run Google's Merge and fix afterwards, which reconciles your imports against the addresses Gmail auto saved from your mail history over the years, the overlap being usually substantial and the one click merge handling it well.

Mailing lists carry the one loss worth knowing in advance: Thunderbird lists flatten to their member contacts in any export, the groupings themselves needing recreation as labels in Google Contacts, a few minutes for the few lists most people keep. The reverse of the trick covered in the Thunderbird lists thread linked alongside, and quicker in this direction since Google labels apply to multi selected contacts in two clicks.

vCard export self mapped perfectly, 280 personal contacts in with zero field fixing. Collected turned out to be 400 entries of pure noise, cherry picked its 9 keepers exactly as advised. Labels rebuilt for my three lists in minutes. Address book chapter closed.