As an administrator, you can help troubleshoot an email that bounces with an error message that doesn’t help fix the problem.
Depending on your account settings or content of the message, there are a number of possible reasons why the message bounced. For example, the message was possibly marked as spam by the outbound spam filter. Or, inbound gateway restrictions might have caused the recipient's servers to reject the message. We have safeguards to keep spammers from signing up for Google Workspace and sending spam.
If your organization's Google Workspace account is mistakenly disabled for spamming, you need to reset your account. For details, contact Google Workspace support.