One-time app passwords
When you enable two-factor authentication, logging into the account on a new device or application should trigger a prompt to confirm your identity, but some older devices and apps — including email apps Thunderbird and Outlook — don’t work nicely with it
The good news is you don’t need to source a separate app or compromise your security — most services that offer two-factor authentication offer what’s known as one-time passwords. These are passwords you can use in place of a regular password to log into an application or device. If an app refuses to work properly even after entering the correct password, try one of these instead.
If you’re a Google user, for example, go to accounts.google.com and sign in. Choose your username, then ‘My Account’. Click ‘Sign-in & security’, scroll down and click ‘App passwords’ beneath ‘2-step Verification’. Choose ‘Select app’ to give your app a name, and a device, then click Generate. Copy and paste the password into the relevant field (tick the option to save it). Now all should be well...