I had talked about OAuth2 briefly a couple weeks ago, but hadn’t really tried it since my Gmail accounts were already setup in Thunderbird. A few days ago I created another Gmail account to handle everything associated with my Firefox Blog as well as Bugzilla emails. I had been using an @ffextensionguru.com address I had setup up through my hosting provider. The problem is this provider only does POP for free. If I want IMAP support then I needed to upgrade to a business email (5 Boxes with Unlimited Space) for about $96 / year. Since I monitor this email address on multiple devices, IMAP is essential. More so, since I have filters setup in Thunderbird to sort my incoming mail based on subject or sender and deposit those messages into a particular folder. So, I just setup another Gmail account for free and then bounce everything from the old @ffextensionguru.com address to the Gmail account.
The account setup process in Thunderbird is pretty much the same in the beginning. Start by going within Thunderbird to File > New > Existing Email Account… The first screen is the same as before where you are prompted to enter how you want your name displayed, the email address and password. When you click ‘Continue’ Thunderbird looks up the server information and will present you with an option to choose IMAP or POP. Again, no changes here.
Choose POP or IMAP then click ‘Done’. Normally, this would be the final step in the account setup and as long as you had enabled “less secure authentication” option within the Gmail account. With OAuth2, upon clicking ‘Done’ you get a Gmail popup screen asking you to authenticate into your account. The first screen will ask for your Gmail address and the second screen will prompt for your Gmail password.
I also discovered while setting up Thunderbird 38.1.0 on my Windows 10 machine, OAuth2 also applies when adding a Google Calendar via the Provider for Google Calendar add-on into Lightning/Thunderbird. You will get the screens similar to above after you enter the Gmail address associated with the calendar you are wanting to add. The only difference is the final screen will be asking about allowing Thunderbird to access your Google Calendar.