How to improve email open rates — and what to measure now that opens are unreliable
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Key takeaways
- Open rate is usually measured with an invisible tracking image; when recipients do not load images, or use Apple’s Mail Privacy Protection, the sender cannot reliably tell whether a message was opened.
- Judge a newsletter on delivery, clicks, conversions, unsubscribes and complaints together, and treat open rate as a secondary signal.
- Five things decide whether people open: reaching the inbox, the sender name, the subject line and preview text, how relevant the list and content are, and send time and frequency.
- There is no “best time to send” that fits everyone; test it by segment on your own list.
- Once a message is open, readability on a phone and one clear call to action decide whether people click.
After a newsletter goes out, the first number many people check is the open rate. It is useful, but it can no longer tell you on its own how a campaign performed. This guide explains how open rate is calculated and why it cannot be taken at face value, then covers what really drives people to open, read and click — and which metrics to watch alongside it.
What open rate is, and how it is calculated
Open rate is generally the number of messages opened divided by the number of messages delivered. Email platforms differ in the details — whether one person opening three times counts once or three times, for example — so compare like with like.
A platform usually knows a message was opened through an invisible tracking image: when the message is opened and the image loads, an open is recorded. That method has two built-in limits:
- If the recipient does not load images, no open is recorded, even if they read the text.
- Mail-app privacy protection. Apple explains that with Mail Privacy Protection turned on, senders cannot see whether you have opened their message — though the protection does not extend to links (Apple Support: Use Mail Privacy Protection on iPhone).
In other words, the more of your recipients use Apple Mail, the less reliable your open data — while click data is far more dependable.
Industry research reflects the shift. The UK Data & Marketing Association’s 2026 survey of 250 marketers found that the share using opens as a primary objective metric fell from 31% to 23%, noting that bot traffic inflates engagement figures and iOS privacy changes have made open rates untrustworthy (DMA Marketer Email Tracker 2026). The bot point is a reminder that clicks, though more reliable than opens, can also include automated clicks — conversions measured on your own website remain the final word.
Which metrics to watch together
| Metric | What it shows | Watch out for |
|---|---|---|
| Delivery / bounce rate | Whether receiving servers accepted the message | Delivered does not mean it reached the inbox |
| Open rate | Roughly how many people opened | Affected by image loading and privacy protection; secondary only |
| Click rate | How many people clicked a link in the message | More reliable than opens; good for comparing versions |
| Conversions | Whether clickers went on to buy, register or enquire | Closest to real results; needs tracking on your website |
| Unsubscribe rate | How many people opted out | A sudden rise points to a content or frequency problem |
| Complaint rate | How many people pressed “Report spam” | Directly affects sender reputation; see thresholds below |
Complaint thresholds are set by mailbox providers. Google, for example, recommends keeping the spam rate in Postmaster Tools below 0.10% and never reaching 0.30%. See How to keep your email and newsletters out of the spam folder — a complete guide for business senders.
Five things that decide whether people open
1. Reaching the inbox
This is the foundation: if a message lands in the spam folder, recipients never see it, however good the subject line. If open rates stay low, check authentication (SPF, DKIM, DMARC) and sender reputation first — see How to keep your email and newsletters out of the spam folder — a complete guide for business senders.
2. The sender name
The first thing people look at in the inbox is often who it is from. A brand or person they recognise gets opened more readily than an unfamiliar name or a noreply@ address. Keep the sender name clear and consistent, and do not change it often; if you send under a person’s name, make it clear which brand they represent.
3. Subject line and preview text
The subject line should say clearly what is inside and why it matters, with the key words first; preview text should add to the subject, not repeat it. Personalisation (a first name, for example) needs fallback text for empty fields. For the full approach with examples, see How to write email subject lines that get opened — preview text, personalisation and A/B testing.
4. How relevant the list and content are
The same message sent to everyone is not relevant enough to most of them. Grouping recipients by interest, purchase history, region or relationship with you — new subscribers, active customers, lapsed customers — and sending each group suitable content is the most dependable way to lift opens and clicks. For how to think about grouping, see How to segment your market.
Deal regularly with long-term non-engagers too: send them a message asking whether they want to stay subscribed, and stop mailing those who still do not respond. Because open data is not fully reliable, when you decide someone is “not engaging”, look at clicks over a longer period as well as opens.
5. Send time and frequency
Send time. You will often read claims such as “Tuesday morning is best”, but no single time suits every list. Industry, job role and whether recipients use work or personal mailboxes all affect when they read email. Instead:
- split your list into two groups, send the same message at different times, and compare clicks and conversions;
- build up results over several sends rather than a single test;
- if your recipients span time zones, send in batches by time zone.
Frequency. A sudden jump in how often you send is the quickest way to trigger unsubscribes and complaints. Tell people at sign-up roughly how often you will write, then keep to it; if you need to send more often, start with your most engaged recipients.
After the open: getting people to read and click
Opening is only step one. Within a few seconds, recipients decide whether to keep reading and whether to click:
- Design for phones first. Many people read email on a phone, so the layout must work on a narrow screen, without tiny text or buttons.
- Make it readable without images. Do not put key information only in images, and give images alt text. For layout, images and mobile rendering, see Email design guide — layout, images, colour, mobile rendering and a pre-send checklist.
- One message, one main action. Rather than ten links, make it obvious what you most want the reader to do, and put that button where it is easy to see.
- Deliver on the subject line. Whatever the subject promised, address it at the top. For writing the body, see How to write email marketing copy — ABC and AIDA frameworks, value-first content and calls to action.
How to keep improving
- Record the same metrics for every send: delivery, clicks, conversions, unsubscribes and complaints, with open rate as a secondary signal.
- Look at trends, not single sends. One campaign’s numbers swing with its content and timing; comparing against the same list’s past performance shows the direction.
- Test one variable at a time — subject line, sender name or send time — and judge on clicks or conversions. For how to run an A/B test, see How to write email subject lines that get opened — preview text, personalisation and A/B testing.
FAQ
What is a good open rate?
There is no standard that fits everyone. Industry, list source and the mail apps your recipients use all move the number, and open data itself is affected by privacy protection. Compare against your own past performance rather than other people’s figures, and rely mainly on clicks and conversions.
Why did my open rate change when clicks did not?
Open data depends on recipients’ mail apps and privacy settings, so a change in open rate does not necessarily mean behaviour changed. If clicks and conversions are steady, there is usually no need to react; if clicks fall too, check whether mail is going to spam.
Why is my open rate high but clicks low?
Common causes are content that does not deliver on the subject line, a call to action that is hard to see, a layout that is hard to read on a phone, or so many links that readers do not know which to click.
Should I delete recipients who never open?
Send them a message asking whether they want to stay subscribed first, and stop mailing those who still do not respond. Do not judge on opens alone, since some recipients’ opens cannot be recorded at all; look at clicks over a longer period too.
Want to see how your newsletters perform on delivery, clicks and conversions? UFOSEND’s EDM email marketing service lets you add merge fields and links to every campaign, and keeps your mail in the inbox with SPF/DKIM/DMARC alignment and Postmaster monitoring.