Email Segmentation by Purchase Behavior
How to segment an online store's email list by purchase behavior: recency, frequency, value, category and engagement, with ready-made segments and what to send.
6 min read
The email metrics that matter for online stores after Apple Mail Privacy Protection: delivery, clicks, conversion, revenue per email, unsubscribes, complaints.
Pidgely teamPublished 6 min readMarkdown version

The email metrics that matter for an ecommerce store are the ones tied to money and to your ability to keep sending: delivery rate, click rate, conversion rate, revenue per delivered email, unsubscribes and spam complaints. Open rate, the headline number of email reports for years, stopped being reliable after Apple Mail Privacy Protection and should be treated as a weak signal. Below are the formulas, where each metric misleads, and how to build an honest dashboard for your store.
Apple describes Protect Mail Activity this way: when it is on, "your IP address is hidden from senders and remote content is privately downloaded in the background" (Apple Mail User Guide). In practice:
The result: inflated open rates, subject-line A/B tests that crown the wrong winner, and "didn't open, resend" automations firing at people who already read the email. Keep the number if you like, but stop using it to decide.
| Metric | Formula | What it answers |
|---|---|---|
| Delivery rate | delivered / sent | Did the email reach the recipient's server? |
| Bounce rate | bounces / sent | Does the list have invalid addresses? |
| Click rate (CTR) | unique clicks / delivered | Did the content create interest? |
| Click-to-open (CTOR) | unique clicks / unique opens | Weak after MPP; handle with care |
| Conversion rate | attributed orders / delivered | Did the email turn into sales? |
| Revenue per delivered email | attributed revenue / delivered | What each send is worth |
| Email AOV | attributed revenue / attributed orders | Big baskets or small ones? |
| Unsubscribe rate | unsubscribes / delivered | Frequency or relevance problems |
| Complaint rate | spam complaints / delivered | Are you losing the right to reach the inbox? |
Two notes:
If the email didn't arrive, nothing else matters. Watch:
4xx): a spike at a single mailbox provider usually means reputation-based throttling.On Pidgely these numbers come from delivery webhooks (email.sent, email.delivered, email.delivery_delayed, email.bounced, email.complained), the per-email log and the Metrics page. Hard bounces and complaints go straight to the suppression list, so you never keep mailing people who shouldn't get your email.
Complaint rate is what mailbox providers watch. Google's sender guidelines ask senders to keep the spam rate reported in Postmaster Tools below 0.30% and recommend staying below 0.10%. For a store sending 100,000 emails in one campaign, 0.30% is 300 people pressing "report spam". That's not many.
What pushes complaints up for stores:
How providers count complaints is covered in feedback loops and complaint rate.
Revenue per email is the metric store owners understand. But "attributed revenue" depends on a choice: which window and which model.
The simplest reliable method today is UTM parameters on every link, with conversions read in your store analytics or platform reports:
https://example.com/products/runner-shoe?utm_source=pidgely&utm_medium=email&utm_campaign=bfcm-2026-early-access&utm_content=heroStandardize utm_medium=email, name utm_campaign so you'll understand it a year from now, and use utm_content to know which block got the click.
Not every email should be judged by the same ruler:
| Type | Primary metric | Warning metric |
|---|---|---|
| Transactional (order, shipping) | Delivery rate and time to deliver | Bounces and delays |
| Abandoned cart | Recovery rate (orders / carts emailed) | Unsubscribes |
| Welcome series | First purchase within 30 days | Complaints |
| Promotional campaign | Revenue per delivered email | Complaints and unsubscribes |
| Post-purchase and reviews | Reviews / delivered orders | Unsubscribes |
| Win-back and replenishment | Reactivated customers / recipients | Complaints |
For order emails, click rate is irrelevant: arriving within seconds is what counts. For abandoned cart emails, the right number is recovery rate, not opens.
Segmenting by these behaviors is the subject of purchase behavior segmentation.
Plainly:
If you only look at six numbers per campaign, make it these:
Compare each campaign with your own recent average, not with generic internet benchmarks: list, niche and frequency change everything. And when revenue rises together with complaints, be suspicious: you are trading today's result for tomorrow's inbox. How to avoid that is in ecommerce campaigns that avoid spam.
As a trend signal, not as a result metric. Since Apple Mail Privacy Protection, remote content is downloaded privately in the background, which records opens that may never have happened. Use clicks, conversions and revenue to make decisions.
Revenue per delivered email, read together with the spam complaint rate. The first tells you whether email sells; the second tells you whether you can keep sending at that pace without losing the inbox.
Add UTM parameters to every link (utm_source, utm_medium=email, utm_campaign) and read conversions in your store analytics or in your platform's reports, such as Shopify or WooCommerce. Pick an attribution window and keep it fixed.
Yes. Open and click tracking is on by default for new domains and can be changed per domain or per send. Machine opens (such as Apple Mail Privacy Protection) and bot clicks are flagged, so metrics show human opens and clicks next to the raw numbers. Delivery events also arrive through webhooks, with a log for every email. For campaign revenue, use UTM parameters and your store analytics.
Pidgely team
Published
We build Pidgely, the email API that gets you to the inbox. We write about what we learn delivering email, citing the standards and mailbox provider guidelines behind every claim.
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