Definition
Email list temperature scoring is a method of assigning each subscriber a numerical "heat" rating based on how recently and frequently they engage with email. The score ranks subscribers along a cold-to-hot spectrum, from those who never open to those who click and convert regularly. Unlike a simple binary engaged-or-not flag, temperature scoring produces a gradient that informs send frequency, targeting, and re-engagement decisions.
How It Works
Temperature scoring combines engagement signals into a single, comparable number for every subscriber. The most common inputs are recency of engagement and frequency of engagement, sometimes weighted by signal type.
- Recency — how many days since the subscriber last opened or clicked; recent engagement raises the score, while long silence lowers it.
- Frequency — how often the subscriber engages across recent campaigns, distinguishing occasional openers from habitual clickers.
- Signal weighting — clicks, purchases, and replies often weigh more heavily than opens, since they signal stronger intent.
- Normalisation — raw signals are converted to a consistent scale, such as 0 to 100 or a cold-to-hot tier, so scores are comparable across the list.
The resulting scores are used to route subscribers into frequency tiers, suppress cold addresses, and prioritise the warmest audience for high-value campaigns, directly supporting email-segmentation.
Best Practices
- Weight clicks over opens — a click indicates active interest, while an open is a weaker and increasingly unreliable signal.
- Decay scores over time — engagement from six months ago should count far less than engagement from last week.
- Define clear tier boundaries — map score ranges to concrete actions, such as daily, weekly, or monthly sends.
- Recompute regularly — temperature changes constantly, so scores should refresh on a daily or weekly cadence.
- Combine with an engagement-score — temperature scoring and engagement scoring complement each other, with temperature emphasising recency.
Example
A retailer scores subscribers from 0 to 100, where recency contributes 60 points and frequency 40 points. A subscriber who clicked three days ago earns a score of 88 and is placed in the "hot" daily tier. Another who last opened 150 days ago scores 8 and is routed to a re-engagement flow rather than the daily broadcast.
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Frequently Asked Questions
Temperature scoring focuses primarily on how recently and frequently a subscriber engages, producing a heat rating. An engagement-score is often broader, incorporating additional behaviours such as website visits and purchases into a single loyalty-style metric.
Any consistent scale works, but 0 to 100 is common because it is intuitive and easy to map to tiers. The key is consistency, so scores can be compared across subscribers and tracked over time.
They should be scored and then excluded or suppressed once they fall below a defined threshold. Keeping the score on record preserves history and supports later re-engagement decisions.
Yes. Routing sends so that cold subscribers receive little or no mail raises aggregate engagement, which mailbox providers read as a positive signal and reward with better inbox placement.