Simply put, if the address and password are correct, blame on Gmail’s new 2-Step Authentication method. Don’t get me wrong, I love it because it’s the best way to protect and secure my Gmail account. And that also doesn’t mean you can’t connect it to your Windows 8 Mail app. It just need one extra step.
Before adding your 2-step authentication protected Gmail to the Mail app,
1. Go to the Authorized Access to your Google Account page, sign in if haven’t.
2. Type in a name to the new password and click Generate password button to generate a new Application-specific password from near the bottom of the page.
3. Go back to Windows 8 Mail app, use the new generated password to add a new mail account there. Note that there is no space in the password, even though it looks like three spaces there.
4. Hoola. All set.
If a Metra App that integrates your Gmail account doesn’t take your password, you probably need to go through this process again to set it up.