The weirdest thing happened this week with one of my engagement programs...the first email had over 96,000 sends, but between the seventh and the eighth email, there was a severe drop of 41,000 sends.
What could account for this? Thanks, all!
Many things can account for this. Since you are looking at emails sent, there may be several smart campaigns running that may be removing people or disqualifying them from moving through the process. This will mean people may not qualify for the remaining sends. For example, I have a smart campaign that triggers off of owner change and then pauses or removes a person from the engagement program. You may have smart campaigns doing this.
Check for following Scenarios
1. Other campaigns targeting same people. They will exhaust their communication limit.
2. Did they hardbouce? (Low probability.. since they received emails 1-7)
3. Did you delete any people from your database?
4. Did you remove/pause people in this campaign?
Best place to start is the activity log, create a smart list and filter for Was sent email #7 AND Not was sent email #8, inspect a few people's activity logs. Then, compare it to some people who Was sent email #7 AND Was sent email #8