We encourage all of our users to insert a postal address in the footer of their newsletter. Spam filters do look for a physical address when they evaluate your emails.
In the United States, it’s required by law to add your address to your commercial emails. This will make you compliant to the CAN-SPAM act, although it’s never really enforced or has it been effective against spam.
Adding your address to the footer of your newsletters
Go to your MailPoet Settings > The Basics where you’ll find this option: