Publish your domain’s DMARC document to prevent phishing and spoofing. For those who’re using a shared IP account from a service provider like SendGrid, don’t setup DKIM and DMARC. It forces your mail streams to get “domain alignment” that can cause your emails to fail authentication and start bouncing. https://cyberattackmodel30527.bloginder.com/27314833/send-bulk-emails-an-overview