Newsletter metrics: why open rates lie and what to track instead

Your newsletter open rate looks healthy, yet the bookings do not follow. That gap is real. The figure counts how many emails loaded a tiny image, and some of those loads come from Apple’s servers and from security filters rather than from people.

This guide explains how an open is counted, why the figure goes wrong, and what I would track in its place. It is part of my guide to sales funnels and newsletters.

How a newsletter open rate is measured

Your newsletter tool adds a tracking pixel to every HTML email: an invisible image, one pixel wide, whose address is unique to each recipient. When an email program downloads that image, the tool records an open for that person.

The open rate is unique opens divided by delivered emails: 300 opens on 1,000 delivered emails gives 30%. The whole calculation rests on one assumption: the image loads when a person reads the email, and only then.

A plain-text email carries no image, so it records no opens at all.

Why open rates lie: three distortions

Apple Mail opens emails nobody has read

Apple introduced Mail Privacy Protection with iOS 15 in 2021. When it is on, Apple Mail downloads remote content, tracking pixels included, in the background, whether or not the person opens the email, and it hides their IP address. Apple’s guide to the feature says it prevents senders from seeing whether you opened their message.

So subscribers who use Apple Mail with the feature on can show as opens whether they read or not, and the open times and locations your tool reports for them tell you nothing about the reader. The feature belongs to Apple’s Mail app: someone reading on an iPhone in the Gmail app is counted the old way.

Blocked images hide real readers

The opposite happens too. Some email programs and company mail systems do not load images until the reader allows it, and some people switch images off for good. They can read your newsletter from top to bottom and never count as an open.

Security filters open and click before your reader does

Many work mailboxes sit behind security filters that fetch images and follow links to check them before the email reaches the inbox, and link previews do something similar. Mailchimp’s help centre names anti-spam security, Apple’s feature and link previews as the usual sources of this bot activity, and notes that a bot’s click is also recorded as an open.

The tell-tale sign is a subscriber who opens and clicks several times within the same few seconds, sometimes on every link of the issue. If most of your subscribers use work addresses, look for this pattern first.

What is a good newsletter open rate?

There is no fixed answer, and two benchmarks covering much the same period show why. MailerLite’s 2025 benchmarks, across 3.6 million campaigns, give an open rate of 43.46% and a click rate of 2.09%. Brevo’s benchmarks, from more than 175,000 customers in 2025, leave Apple’s automatic opens out and give 20.73% opens and 2.27% clicks.

The two customer bases and calculation methods differ, so the comparison is rough. Still, one open rate is about double the other while the click rates sit within 0.2 points of each other: that is the argument of this article in four numbers.

Click rates also vary by sector: from 0.83% to 4.90% in MailerLite’s data. The benchmark that matters most is your own: note your click rate over your last six issues and compare each new issue with it.

What to track instead

These are the figures I would put on a newsletter report.

Click rate, on delivered emails

Avoid the click-to-open rate (clicks divided by opens): it inherits every flaw of the open. If your tool offers bot filtering, switch it on before you compare issues. Mailchimp warns that opens and clicks drop significantly once it is on, which is rather the point.

An issue built around one clear link gives you a cleaner reading, and my ideas for a B2B newsletter will help you find things worth clicking.

Replies

For a small team selling a service, a reply is worth more than a click: it is the start of a conversation. End an issue with a real question. Replies land in your inbox rather than in the newsletter report, so keep a tally per issue.

Conversions: booked calls and sales

Add UTM parameters to every link in an issue, so that GA4 can tell newsletter visits apart:

https://example.com/audit/?utm_source=newsletter&utm_medium=email&utm_campaign=2026-10

Then create an event in GA4 for visits to the booking confirmation or thank-you page, and mark it as a key event (what GA4 used to call a conversion). From then on, “how many calls did October’s issues bring?” has an answer. My step-by-step guide to UTM links and GA4 covers the setup.

Unsubscribes and spam complaints

An unsubscribe is a polite no; a spam complaint is a loud one, and it hurts your deliverability. Gmail wants the spam rate shown in Google Postmaster Tools below 0.1%, one complaint per 1,000 emails, and never at 0.3% or higher. On a small list, Postmaster Tools may show incomplete data on quiet days, so read it over the month. My guide to the Gmail, Yahoo and Outlook sender rules explains the rest.

Read unsubscribes issue by issue rather than as an average: a spike after one issue tells you what that issue did differently.

List growth and churn

Count net growth over a month, and churn as the people who left divided by the list size at the start of that month. If people leave in their first weeks, look at your welcome sequence before anything else.

A/B test subject lines on clicks, not opens

A subject line test judged on opens is now partly a test of noise. Machine opens land on both versions whatever the subject line says, so the gap between them shrinks and the winner can be down to chance. Judge tests on clicks, or better, on replies and conversions. If your tool picks the winner automatically, check which metric it uses.

On a list of a few hundred people, one test proves little: run the same comparison over several issues before you change your habits. That is how I run cold email tests for clients. The emails are plain text with a phone number and no links, so there are no opens or clicks to count, and versions are compared on the responses they bring. Over time, the copy that gets answers wins.

Engagement segments: who is really reading

Opens are also a poor way to find inactive subscribers. Apple Mail users look active for ever, and image blockers look inactive while they read every issue. Build segments on clicks and replies instead. For a weekly newsletter, for example:

• Engaged: clicked or replied in the last 90 days.
• Quiet: no click for 90 days, but at least one in the last six months.
• Inactive: no click for six months.

Double the windows for a monthly newsletter. Send the inactive segment one short email asking whether they still want to hear from you, and remove those who do not click to stay.

Tracking pixels and consent in the UK and France

The ICO’s guidance on email marketing says the PECR rules on marketing emails apply to the email itself, while tracking pixels fall under the separate rules on storage and access technologies, regulation 6 of PECR: if your newsletter contains a pixel, you must comply with both (ICO guidance). That means clear information and consent of the UK GDPR standard unless an exception applies, and the ICO says these rules apply to every type of subscriber, companies included. The Data (Use and Access) Act 2025 added new exceptions in February 2026 and lets the government add more, so this is the position as of 19 October 2026.

In France, the CNIL adopted a recommendation on email tracking pixels on 12 March 2026 and published it on 14 April 2026. Under its reading of article 82 of the French Data Protection Act, tracking opens for marketing needs the recipient’s prior consent, separate from their agreement to receive the newsletter, business addresses included. The exemptions are narrow, such as security and measuring deliverability. Tracked links are not directly covered, but the CNIL says the purpose counts, not the technique.

Since this article argues for judging a newsletter on what readers do, switching open tracking off, or asking for consent to it, costs you little. My guide to newsletter consent covers the sign-up side. This is general information, not legal advice: if your list is large, or you combine email data with advertising, an hour with a privacy lawyer or a DPO is money well spent.

Your monthly newsletter report: a checklist

Once a month, with bot filtering on if your tool has it:

1. Note delivered emails, unique clicks, unsubscribes and complaints for each issue of the month.
2. Count the replies each issue received.
3. In GA4, look at sessions with the medium “email” and the key events they led to: booked calls, quote requests, sales.
4. Check the spam rate in Postmaster Tools.
5. Work out net list growth and churn.
6. Decide one thing to keep, change or drop next month.

If the report starts taking longer than writing the issue, automate the collection into one spreadsheet or dashboard.