With two-factor authentication, you need an app-specific password to sign in to your account using third-party apps like Canary Mail. Follow these steps to generate an app-specific password:
- Sign in to your Apple ID account page.
- Scroll down to the Security section.
- Below App-Specific Passwords, click Generate Password.
- Follow the steps on your screen.
- When complete, open Canary and add your iCloud account as usual.
- When prompted for your iCloud e-mail address and password, enter the App-Specific Password in the password field.
- Complete set-up.