Although all our servers are housed in data centers that have all kinds of security, and strategically located throughout the world, what options do you have if the service is interrupted for a few hours, and you need to receive an email urgently?

     Well, a redundant service, basically consisting of a rescue server. This agrees that this geographically distant from the main service, and the smtp sending protocol itself will manage that the redundant server receives the mails when the main server is down.