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
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ARPU (Average Revenue Per User)
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Frequently Asked Questions
Good practice here means handling Email Campaign Efficiency Score in a way that is relevant, timely, and honest for your audience. A composite metric that measures campaign performance relative to its cost, effort and audience size to enable fair comparison across different campaign types. Done well, it improves engagement and builds trust; done poorly, it creates friction that costs you results.
Because it touches the parts of email that drive outcomes: relevance, trust, and delivery. Small improvements compound, while repeated mistakes quietly erode the health of your programme.
The most common problems are treating Email Campaign Efficiency Score as a one-off task, ignoring what the data says, and copying competitors without testing. All three lead to effort that does not translate into better results.
Compare the metrics it should influence — engagement, conversions, and deliverability — before and after you make changes. Trends over time matter far more than any single send.
It supports the same goal as the rest of your email programme: the right message to the right person at the right time. Aligned with segmentation and automation, it reinforces everything else rather than competing with it.