e371f003_liverability___Act_On_Software__Are_You_a_Legitimate_Mailer_
Spammers use bogus entries in domain registrations, or “private” or “hidden” annotations. [Are You a Legitimate Mailer?] 
Be visible and public in your domain and hosting registrations.
Best Practices in Email Deliverability - Act-On Software
Are You a Legitimate Mailer?