How does DESelect Engage deal with unplanned Sends?

an unplanned send is a campaign send (also referred to as just "send/s") that happens through journey builder, where engage has not been able to calculate in advance if a person should be excluded or included for this send this can happen in the following situations a send happens more than 3 days after the planned send date a send is added to the calendar for the same day, after the daily calculations have run a send happens for an unscheduled send, meaning a send without a send date whenever such unplanned sends occur, engage does the following check if based on the recent sends and sends planned in the near future, there is a slot available to send this send if a slot is available, the contact is considered included for this send if no slot is available, look at the other planned sends and their priorities if the current send has a higher priority than the planned ones, include the contact in this send and exclude the contact from the send with the lowest priority some example scenarios (all assume 1 saturation control rule of maximum 3 emails per week) a) 2 emails sent in the last 3 days, no sends planned in the next 3 days when the unplanned send comes in, it sees that there are no planned sends in the next 3 days, so there is 1 slot available before hitting the limit of 3 emails per week the contact will be included in the unplanned send b) 2 emails sent in the last 3 days, 1 send planned in the next 3 days as there is already one planned send in the next 3 days, all 3 slots that the rule allows for have been assigned 2 of those were in the past so they cannot be changed now the unplanned send and the other planned send are competing for the remaining slot to decide which sends gets sent, deselect engage will look at the priority of the sends if the unplanned send has a higher priority than the planned send, the contact will be excluded from the planned send and included in the unplanned send c) 3 emails sent in the last 7 days as all available 3 slots per 7 days have already been used, the contact will be excluded from the unplanned send, as otherwise the rule of 3 emails per week would be breached d) no emails sent in the last 7 days, 2 planned in the next 3 days 2 of the 3 available slots per 7 days have been assigned to sends in the next 3 days when the unplanned send comes in, there is still one slot available, so the contact will be included in the unplanned send e) no emails sent in the last 7 days, 3 planned in the next 3 days this scenario is similar to scenario b all available slots have already been filled engage will compare the priority of the planned sends occupying the slots with the priority of the unplanned send if the unplanned send has a higher priority than any of the planned sends, the contact will be excluded from the one with the lowest priority in favor of the unplanned send