You should be worried if you see a high number of emails being sent from an unfamiliar IP address using your domain. This can mean that your domain may have been compromised by spammers.
It’s important to ensure all of your emails are properly authenticated with SPF, DKIM, and DMARC. You can enforce a “p=reject” policy after you’ve confirmed that only legitimate emails are being sent from your domain.
This will protect your brand and prevent unauthenticated emails from being sent on your behalf.