You received a notification letting you know that emails you have sent in bulk from Copper haven't been delivered. What could be the issue?
Check the following:
Is Gmail experiencing problems? Check the Google's status page: https://www.google.com/appsstatus#hl=en&v=status
Is Google Sync enabled?
Go to Settings > Company Users > Edit your record > make sure Google Sync is enabled.
Are the Google permissions granted?
Check if Copper is no longer granted access to your correct Google account. You can see your permissions here:https://security.google.com/settings/security/permissions?pli=1. Remove Copper off this list and we will automatically notify you with a "Reconnect" toaster in the bottom left corner of Copper or when you log in next.
Try sending the email that failed, again.
If the above fails, it is possible that you're over the email limit imposed by Google. Try sending the email again tomorrow.