Definition
An email campaign efficiency score normalises campaign performance by accounting for differences in cost, audience size and effort. Raw metrics like revenue and clicks favour large-list campaigns. Efficiency scores level the playing field by dividing outcomes by inputs. Common formulations include revenue per thousand emails sent, profit as a percentage of campaign cost, engagement rate relative to send frequency, or a weighted composite of open rate, click rate and conversion rate divided by cost per send.
Why It Matters
- Enables fair comparison between campaigns sent to different list sizes
- Identifies campaigns that generate high absolute revenue but low efficiency
- Highlights smaller campaigns that may outperform on a per-contact basis
- Provides a consistent benchmark across automated and broadcast campaigns
Best Practices
- Calculate efficiency scores for every campaign and use them alongside absolute metrics
- Use revenue per thousand sends as a baseline efficiency metric before building composite scores
- Compare efficiency scores within campaign types rather than across fundamentally different formats
- Review efficiency trends over time to identify whether campaign quality is improving or declining
- Include efficiency in campaign reporting to provide context alongside total revenue and click figures
Related Glossary Terms
Abandoned Cart Email
An abandoned cart email is an automated message sent to customers who added items to their online shopping cart but left without completing the purchase. It is one of the highest-converting email types in ecommerce.
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 Threshold
A bounce rate threshold is the percentage of hard or soft bounces at which email platforms and ISPs begin to penalise sender reputation, typically around 2-5%.
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 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.