Dovesoft does!
Gmail is introducing stricter rules for bulk sender over 5,000 emails a day. To help you land your messages in the inbox, Dovesoft already makes the sender authentication process (SPF, DKIM, DMARC) as easy as possible. It streamlines DNS records settings and has rigorous internal anti-spam policies to help you keep below 0.3.% spam rate reports. Dovesoft also automatically inserts an unsubscribe link header in messages so you don't have to worry about it. And finally, Dovesoft offers double opt-in to help you email only willing contacts who are unlikely to mark you as spam.