How to create an app password for Gmail?

https://myaccount.google.com/apppasswords

How to put an email address in white list or black list on Google Workspace?

https://support.google.com/a/answer/2368132

Prevent mail to Gmail users from being blocked or sent to spam

Prevent mail to Gmail users from being blocked or sent to spam

https://support.google.com/mail/answer/81126

How to prevent your emails from going to spam

How to prevent your emails from going to spam

https://community.cloudflare.com/t/how-to-prevent-your-emails-from-going-to-spam/175552