When attempting to send mail, you receive the following error in a bounced email:
SPF must allow google servers to send mail on behalf of your domain
SPF defines the mail servers that are allowed to send mail for your domain. If you are sending emails for your domain via G Suite, you will need to add Google's servers to your SPF record in order for them to be authorized to deliver your mail.
Consult Google's documentation on SPF for how to properly configure your SPF record for use with Google's servers:
Google's documentation on "Help prevent spoofing and spam with SPF"