A program on the portal server checks in at regular intervals of about 30 minutes, to see if a connection can be made to the customers mail server and checks if a working SMTP session is available. If so the mails from the Continuity Service are sent to the customers designated mail server. If not? The Continuity Service continues to function until such time as a viable connection can be made.
The above process will only work upon the first instance of an unsuccessful mail delivery. If for some reason the Continuity Service is activated at a later point of time the mails already in the gateway queues will not be redirected to the Continuity Service/portal account.