How to disable `New Account Setup` wizard in Mozilla Thunderbird

I don't know of any way to disable the new account wizard but you could add an account with fake information and then set it to not automatically check the mail for that account. Thunderbird should stop bugging you about adding a new account and it shouldn't cause any problems (unless you click 'get mail' for that account).

My use case - use Thunderbird to view .eml files.

What worked for me.

• Open an email with Thunderbird.
• Cancel the setup wizard.
• From the opened email view, go to Edit -> Account Settings.
• Go to Account Actions -> Add Feed Account.
• Click on Next, then click on Finish.

Done. You won't be asked to create an account again.

Set Thunderbird to "offline mode", then go through the wizard. It won't attempt the tests and you can select "advanced" and it should drop you back to the accounts configuration page and continue setting up there.