Set up SPF to prevent spammers from sending unauthorized emails from your domain. This type of spamming is called spoofing. Sender Policy Framework (SPF) is an email security method to prevent spoofing from your domain.
Spoofing is a common unauthorized use of email, so some email servers require SPF. If you don’t set up SPF for your domain, messages could bounce or could be marked as spam.
Learn more at the Google support site using the link below: