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CloseReview for Provider for Google Calendar by LW
Rated 5 out of 5 stars
It turns out Thunderbird already supports Google Calendar by default:
https://support.mozilla.org/en-US/kb/using-lightning-google-calendar
No need for any add-ons!
I followed the steps from the How To and added my calendar without any issues.
It is now natively supported and smoothly syncing with Google Calendar!
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