Google mail no longer works with Apple mail. I am getting an error message from Google:

none of these suggestions work as the moment you click "Add new account" and select Google, the error 400 message pops up. Clearly this is an issue for several users as more and more of these posts are popping up on these boards.

romac99 wrote:

none of these suggestions work as the moment you click "Add new account" and select Google, the error 400 message pops up. Clearly this is an issue for several users as more and more of these posts are popping up on these boards.

so what happens when you contacted Google about not being able to add their mail account, you'll need 2 factor authentication or app specific passwords to use their account.

It may just need an App Password separate from the gMail password…

https://support.google.com/mail/answer/185833?hl=en-GB

Apple Mail won't sign in to Google account - Apple Community

my iMac has OS Yosemite 10.10.5 Does this… - Apple Community

my iMac has OS Yosemite 10.10.5 Does this… - Apple Community

gmail on mail Version 11.5 (3445.9.1) - Apple Community

gmail on mail Version 11.5 (3445.9.1) - Apple Community

Note from PrestoWebDesign…

Trying to add Gmail account to Apple Mail… - Apple Community

Trying to add Gmail account to Apple Mail… - Apple Community

Santadeb wrote:

This is the error message. How do I fix this?

Sign in with Google

Authorization Error

Error 400: invalid_request

You can't sign in to this app because it doesn't comply with Google's OAuth 2.0 policy for keeping apps secure.

You can let the app developer know that this app doesn't comply with one or more Google validation rules.

Learn more

Request Details

The content in this section has been provided by the app developer. This content has not been reviewed or verified by Google.

If you’re the app developer, make sure that these request details comply with Google policies.

·       redirect_uri: urn:ietf:wg:oauth:2.0:oob

The error message points to google and is coming from google. So contact google

This is happening to me as well, OSX El Capitan, Mail 11.5... Just can't add new google account into Apple Mail, incredibly frustrating going through all these updates which disrupt and take hours of troubleshooting before users can continue actual work that they need to do.