If your Gmail messages stop appearing in Apple Mail, or you can’t send emails, or you are getting an error message, here are some tricks to try.
- Quit Apple Mail and re-launch mail.
- Restart your computer.
- Change your DNS settings . I describe how to do this here.
- Quit Mail, go to System Preferences, Internet Accounts, select your account and untick the ‘Mail’ option. Start mail. Quit Mail. Go back to System Preferences, Internet Accounts, select your account and re-tick the ‘Mail’ option. Start mail.
- Try accessing your email from your iPhone or a different computer. If it doesn’t work there either, it may be a problem with Google. Check here to see if Gmail is working.
If these don’t work, try this guide from Apple. It’s pretty good but it doesn’t have step 3 above which seems to be a major cause of Mail not working.