How does DESelect Engage decide whether somebody should receive a Send or not?

Decisions are made based on:

1. messages sent to a contact in the recent period
2. planned Sends a contact is targeted for and the priorities of those Sends
3. the saturation control rules that have been defined for the contact category of the contact

How far DESelect Engage looks into the past and the future, depends on the time frame that's used in the relevant rules that have been defined.
Engage always considers today as the middle of that timeframe.
So, for example, if a rule is defined that 5 campaign Sends (also referred to as just "Send/s") can be sent per 30 days, it will look back at the sent Sends in the last 15 days and look forward to the planned Sends in the next 15 days.

Engage then evaluates all planned Sends in the next 15 days for which this contact is targeted. It will reserve time slots for these Sends when slots are available. In case the contact is targeted for more Sends than the rules allow, slots will be reserved for the Sends with the highest priority.

From the example above: if the contact has already received 3 Sends in the last 15 days, according to the rules, the contact could receive max 2 more Sends. If the contact is targeted for 4 future Sends, the 2 available slots will be reserved for the 2 Sends with the highest priority. The contact will be excluded from the other 2 planned Sends with lower priority.

Some edge cases:

- What happens if a Send goes through Journey Builder on a different date than the original send date in Engage?