Definition
Engagement velocity is the speed and direction of change in subscriber engagement over time. While a standard metrics report shows current open rates and click rates as static numbers, engagement velocity shows whether those numbers are rising, falling or holding steady — and at what rate.
A list with a stable 25 percent open rate that has declined from 30 percent over six months is in trouble, even though the current number looks healthy in isolation. Engagement velocity catches the trend behind the snapshot, giving teams time to intervene before the situation becomes critical.
Calculating Engagement Velocity
Compare the current period's engagement metric against the same metric from a previous comparable period. Express the change as a percentage. For example, if the monthly open rate dropped from 28 percent to 24 percent, the velocity is negative 14 percent month over month. Tracking velocity over rolling periods reveals whether the decline is accelerating or stabilising.
Best Practices
- Track velocity for open rate, click rate and conversion rate separately — they often move at different speeds
- Set velocity thresholds that trigger investigation; a 10 percent drop in monthly open rate velocity warrants review
- Combine velocity data with list growth data — growing a list while engagement velocity declines suggests acquisition quality problems
- Present velocity trends alongside absolute metrics in performance reports so stakeholders see both the current state and the direction
Related Glossary Terms
A/B Testing
A/B testing in email marketing is the practice of sending two variations of an email to a small sample of your list to determine which version performs better before sending the winner to the remaining subscribers.
ARPU (Average Revenue Per User)
ARPU (Average Revenue Per User) is a metric that measures the average revenue generated per email subscriber over a specific period, used to evaluate list value and campaign effectiveness.
Attention Rate
Attention rate is the percentage of email opens that last longer than 5 seconds, distinguishing genuine reads from passive opens, preview-pane views, or Apple MPP auto-loads.
Bounce Rate
Email bounce rate is the percentage of emails that were rejected by the receiving server before reaching the recipient. It is a key indicator of list health and data quality.
Campaign Internal Rate of Return (IRR)
Campaign IRR is the annualised return rate earned by an email campaign, accounting for the timing and magnitude of costs and revenue across the campaign's full lifecycle.
Campaign Lifted Revenue
Campaign lifted revenue is the additional revenue generated by an email campaign beyond what would have occurred without it, measured via a holdout group or statistical lift analysis.