You might notice that your number of engaged contacts for broadcast campaigns increases and decreases over a short period of time.
This is because of the way we calculate individual contact engagement scores.
A contact becomes unengaged (i.e. an engagement score of 0) when they have been sent at least six email in the past 180 days, but they have not opened or clicked any of them.
At this point the contact is assigned the status No engagement, and can be excluded from broadcast campaigns.
If this contact does not receive new campaigns (possibly due to being excluded as unengaged), the campaigns they were previously sent will eventually fall outside of the 180 day time window.
When this happens, starting from the moment there are six sends or fewer in the time window, Ometria will combine the contact's engagement score with the account average.
When there are no previous sends in the 180 day window (i.e. 180 days after the last send), Ometria only uses the account average for the contact's engagement score.
This means that the previously unengaged contact will now have the a Medium engagement status.
This process makes sure your contacts who are still subscribed have the opportunity to re-engage.
See also: Email engagement bands in Ometria