Widely covered in the news, Google had a ~50 minute downtime in the December 14 early morning (Pacific Time) where most of its services (GMail, Youtube, Google Drive, etc.) with exception of Google Search is down.
Today, we received additional reports where emails sent to GMAIL.com email accounts are getting bounce back saying the recipient does not exist. You can see example of support request here:
5.1.1 The email account that you tried to reach does not exist. Please try 5.1.1 double-checking the recipient's email address for typos or 5.1.1 unnecessary spaces. Learn more at Action: failed Final-Recipient: rfc822;
Summary: If you are seeing bounce back from Gmail addresses from your mail service, please note that this is an issue with the recipient’s GMail service, not with your mailbox. Google is likely still recovering from and having lingering issues that may or may not be related to the Dec 14 downtime issue.
If you are seeing bounceback from non-gmail services, then it is another issue.
Solution: Try re-sending the email again in a few hours or the next day. We do expect Google to fix this in a timely manner, given the severity of this issue.
If you have any questions please feel free to contact your support / sales representative. Or email@example.com