The reason I need to do this is because some time ago Gmail blocked access to one of my email accounts due to its obnoxious authentication policies.

Not sure what this means. You'd need to be more specific.

I am unable to pass the Google authentication screen for this gmail account so now I cannot use it with Thunderbird either.

Please post your Troubleshooting Information. At the top right of the Thunderbird window, click the menu button , then select Help > Troubleshooting Information. Press the "Copy text to clipboard button" and paste the information into your reply.

The reason I am making this post is that I have Thunderbird on an older Windows installation and the Gmail account works there.

If 'an older Windows' installation means an unsupported version of Window, and potentially also an unsupported version of Thunderbird, then this sounds like a dead end. It would make way more sense to fix the original problem.

Is there any collection of files in the profile folder that would facilitate copying an email account from one profile to another?

There isn't. You could copy over the entire profile, and then delete the stuff you don't want on the Ubuntu machine.

Thanks for the reply. It appears that your last sentence is also a direct answer to my question. However, I will add the clarifications that were lacking in my original post, maybe someone can suggest a solution.

Gmail is not allowing me to login into my account because it "doesn't recognize the device". I'm sure you've seen this before, it happens all the time when cookies are cleared or when you move to a different browser. Even though you have the correct credentials, you need to prove to Google that it's really you. Since I don't have any use for 2 factor authentication and I neglected to set a recovery email address (something that I also wouldn't have any use for if it weren't for these authentication shenanigans), the only way I can prove to Google it's me is to remember the answer to a stupid security question that I don't even remember setting up. I have been using this email account on the same device for more than 10 years, which Gmail could check if they'd care, but some cookies were lost and now none of that matters.

My Thunderbird used to have my credentials saved back when I could authenticate so I didn't need to go through Gmail's authentication screens to use that email account in Thunderbird. That changed when a power failure rebooted my PC and Thunderbird posted a bunch of authentication failures for the email accounts that I have set up. I fixed those, that is not the issue I want to raise here. But I had to authenticate again on all email accounts.

The Windows installation of Thunderbird means a very much supported, updated version of Thunderbird for Windows. Though I don't know if this is relevant, since you mention it is not possible to transfer accounts anyway.

Google sort of requires OAuth2 authentication these days. This also applies to Thunderbird. OAuth2 is basically a web based authentication method, so not surprising it uses cookies. Again, that also applies to Thunderbird. The benefit of using OAuth2 is that Thunderbird only remembers an authentication token, but not your Google account password. And it just works once going through the initial setup and authentication process.

Google will let you jump through some other hoops when not using OAuth2 authentication, such as 2-step authentication, or app specific passwords. So there's not much to gain when bypassing OAuth2.

If you don't have any of those authentication issues with your Thunderbird installation on the Windows computer, that may mean it's not set up (yet) for OAuth2 authentication. Rest assured, it's only a matter of time until Google gets you.

Wrt to your Google authentication issues, none of that is related to Thunderbird. I'd recommend though to look through your Google account options, and put a reliable account recovery mechanism in place. Otherwise it will likely bite you at some point in the future.

You are right that Google authentication issues are not related to Thunderbird. That's why I didn't want to make my post about this. My question was about whether Thunderbird allows moving one email account from one profile to another with all cookies or authentication tokens, as it is the case. And you already answered that it is not possible. So thanks again for your help.

Edit: Could that OAuth2 authentication token be copied and pasted between profiles? It could be that my Windows Thunderbird is using OAuth2 as well (I'll have to check), which means that it could have an authentication token.

Hello there we have read your message. We try to help you.

https://support.mozilla.org/en-US/products/thunderbird/install-migrate-and-update/copy-your-personal-information-one-thunderbird-another

https://support.mozilla.org/en-US/kb/using-identities

https://support.mozilla.org/en-US/kb/configuration-options-identity

Greetings Firefox volunteer.

Thank you. Moving the entire profile is fine but unfortunately there seems to be an incompatibility between the Windows and Linux versions of Thunderbird so it will not start with the transfered profile.

My Windows and Linux Thunderbird installations both use OAuth2 for that gmail account. So I was hoping that the authentication token used by gmail accounts is stored in a file that I could transfer from one profile to another.