Email marketing KPIs: the metrics that actually matter
Choose email KPIs around the outcome you want: activation, a paid upgrade, or another product action. Track delivery and complaints alongside conversions, and keep attribution separate from evidence that email caused the result.
Delivery and reputation
Delivery rate. The share of sends accepted by receiving servers. Investigate a decline using bounce responses, authentication checks, and list quality. Acceptance does not guarantee inbox placement.
Bounce rate. Separate permanent failures from temporary ones and inspect the reported reasons before deciding what to change.
Spam complaint rate. Monitor it alongside delivery. Gmail requires spam rates reported in Postmaster Tools to stay below 0.3 percent. Aim below 0.1 percent, and investigate increases before they affect more sends.
Engagement
Open rate. Useful as a trend, unreliable as an absolute. Apple Mail Privacy Protection pre-loads images and inflates opens, so treat it as directional.
Click rate. Clicks divided by emails delivered. Compare clicks with the product actions that follow them.
Click-to-open rate. Clicks divided by opens. Inflated opens also distort this ratio, so it cannot reliably tell you how many people read the email before clicking.
Outcomes
Conversion rate. Choose the outcome first: a signup, purchase, or reply. Divide recipients who completed that outcome by delivered emails, then multiply by 100. For example, 147 conversions from 9,800 delivered emails is 1.5%. Use the same attribution window for both counts and count each recipient once per outcome. If you divide by clicks instead, label it click-to-conversion rate so the two measures are not compared as equivalents.
Revenue per email or per recipient. Define which revenue counts and use a consistent window and denominator. A lower open rate can still accompany higher revenue per recipient.
Measure activation and paid upgrades
Define activation as a product action, such as publishing a first project. Record userId, accountId, the qualifying event, and its timestamp in your app or analytics. For paid upgrades, use the first successful paid subscription or payment from your billing system. An upgrade-page click is a separate funnel step.
Choose one reporting unit and window before sending. For a seven-day activation report, freeze the eligible recipients who have not yet activated at delivery, then count each recipient whose first activation occurs in the following seven days. For team products, count distinct eligible accounts and join users to accounts so five teammates do not become five paid upgrades.
Illustrative example: 1,000 eligible users receive an onboarding email and 120 first activate within seven days. The recipient conversion rate is 120 ÷ 1,000 = 12%. A separate upgrade campaign reaches 500 eligible free accounts and 25 become paid within 14 days, giving an account conversion rate of 5%. These are different cohorts and denominators.
Tag email links with consistent campaign UTMs and join authenticated visits to product outcomes using stable IDs. Keep personal data out of URLs. Report click-attributed conversions separately from all conversions after delivery. If several emails precede one upgrade, choose a single attribution rule or label the results as overlapping assisted conversions. Do not add them together as unique revenue.
These counts describe what happened after email. A randomized holdout estimates how much email changed the outcome.
Track campaign outcomes with Loops Goals
Create a goal in Settings → Goals. Set eligibility, a conversion target based on contact properties, and a measurement window. For example, keep a paid property synced from billing and use it as the target for an upgrade campaign. Attach the goal on the draft campaign’s Send page before scheduling. Goals cannot be added retroactively to sent campaigns.
Read unique contacts evaluated and converted separately from enrollments. One contact can enter more than one measurement window, so enrollment totals are not a count of unique people. Keep account-level revenue and deduplicated billing outcomes in your own analytics. A campaign goal measures conversions after delivery and does not establish causal lift.
List health
Unsubscribe rate. Compare it with your previous sends. A sudden increase is a reason to review audience selection, frequency, and content.
List growth. Report new subscribers minus unsubscribes and removed addresses over a defined period. To express it as a rate, divide that change by the starting list size.
How to use them
A key performance indicator (KPI) is a metric chosen to measure progress toward a specific goal. Pick one primary KPI per send and define the outcome and measurement window before sending. Watch delivery rate, spam complaints, and bounce rate alongside it because they protect future sends. Treat open rate as a trend, and compare results with your own history and audience segments. Record assisted conversions separately when an email contributes to a later signup or purchase.
In Loops, sends and workflows report opens, clicks, bounces, spam complaints, and unsubscribes in one place, so you can watch reputation and engagement together.
Frequently asked questions
What is the most important email marketing KPI?
Is open rate still useful?
What is a good email bounce rate?
What spam complaint rate is too high?