Gmail breakdown causing users to get error messages
Some users are also experiencing high latency and other issues.

Gmail is a little out of whack.
If you're getting odd error messages when trying to send messages through Gmail on Tuesday, you're not alone. Google reported on its status dashboard a "significant subset" of users is experiencing error messages, high latency and other unexpected behavior.
Some users are reporting that they're receiving bounceback messages when trying to send an email to a Gmail address. Encrypted email service ProtonMail reported that the email bouncing issue appears to be widespread.
"Gmail is currently suffering a serious outage and permanently bouncing emails sent to Gmail users." Proton said in a tweet Tuesday. "The problem is on Google's side, and is impacting all email traffic (not specific to ProtonMail). We will continue monitoring the situation."
Gmail is currently suffering a serious outage and permanently bouncing emails sent to Gmail users. The problem is on Google's side, and is impacting all email traffic (not specific to ProtonMail). We will continue monitoring the situation.
— ProtonMail (@ProtonMail) December 15, 2020
Google said Tuesday afternoon it's "continuing to investigate this issue."
The disruption comes after a Google services outage on Monday affected Gmail, YouTube, Google Drive, Google Hangouts and Google Meet.