This is a dud product with inferior spam filtering versus alternatives like SpamHero, and the continuity feature is essentially marketing fluff. Failed deliveries, for example, they don't count it as an issue so those messages won't be queued for another delivery attempt. As I understand it from talking to their support, if the server pings or sends any response at all, then Mail Assure will not keep a copy. It will also weirdly mark messages during that outage as rejected, so it's not like Mail Assure doesn't know that the message never reached the user(s).