Key takeaways
- Open rates are a weak signal now. Apple Mail Privacy Protection preloads images, including tracking pixels, so many “opens” are machine opens, while security scanners and image blocking distort the numbers further.
- Lead with clicks, conversions and revenue, and use opens only as a rough trend.
- Real drops usually come from deliverability. Gmail and Yahoo began enforcing bulk sender rules in February 2024, and Microsoft required SPF, DKIM and DMARC for senders of more than 5,000 emails a day to Outlook.com addresses from May 5, 2025.
- Predictable subject lines, the wrong sending frequency, list decay and drifting content also push engagement down.
- Authenticate your domain, clean your list, segment and test subject lines and send times to improve the factors you control.
If your email open rates fell, or jumped and then fell, you are not alone. Part of the change comes from how opens are measured, and part from mailbox providers tightening the rules for bulk senders. This Emulent guide explains why open rates are less reliable, what actually causes real drops and how to fix what you can control.
Why are open rates less reliable in 2026?
Because an open is recorded when a tiny tracking image loads, and that no longer means a person read the email.
- Apple Mail Privacy Protection: since iOS 15 in 2021, Apple Mail can preload message content, including tracking pixels, when the email arrives, whether or not the recipient reads it. That inflates opens for Apple Mail users.
- Security scanners: corporate email security tools load links and images to check for threats, which can register opens and even clicks from bots.
- Image blocking: some clients and users block images by default, so real readers may never register an open.
- Automated tests: A/B tests and send-time tools that pick winners by opens can choose the wrong version when opens are mostly machine-driven.
Emulent moved client email reporting away from open rate as a headline metric. We now lead with click rate, conversion rate and revenue per email, and treat opens as a directional signal.
What actually causes open rates to drop?
Set measurement aside, and real declines usually trace back to a few causes.
| Cause | What it means |
|---|---|
| Deliverability problems | if mail lands in spam or Promotions, people never see it. Google’s email sender guidelines require bulk senders to authenticate mail, offer one-click unsubscribe and keep spam complaint rates low, and Microsoft announced on its Defender for Office 365 blog that Outlook would require SPF, DKIM and DMARC for domains sending more than 5,000 emails a day. |
| Subject line fatigue | patterns such as “Monthly newsletter, March 2026” teach subscribers that every email looks the same. |
| Frequency mismatch | too many emails cause people to tune out or complain; too few and they forget who you are. |
| List decay | people change jobs, abandon addresses and lose interest. Without regular cleaning, a growing share of the list never engages. |
| Content drift | if emails stray from what subscribers signed up for, or repeat the same format every time, interest fades. |
How do you improve open rates with the factors you can control?
Fix deliverability first, then make each email more worth opening.
- Authenticate your sending domain with SPF, DKIM and DMARC, aligned with your From address, and monitor results in Google Postmaster Tools and your email platform.
- Test subject lines on every major send, and judge winners by clicks or conversions rather than opens.
- Clean the list regularly: run a re-engagement series for subscribers with no clicks, site visits or purchases in several months, then suppress those who do not respond. Remove hard bounces immediately.
- Segment and personalize by interest, behavior, industry or stage, so each group gets content that fits.
- Test send days and times for your audience. Business audiences often engage midweek mornings, but your own data is the better guide.
- Use a recognizable sender name, such as a named person at your company, and keep it consistent.
- Make emails worth opening: lead with a specific benefit in the subject line and deliver on it in the first lines of the email.
In one Emulent client engagement, removing several thousand inactive subscribers, putting DMARC in place and testing subject lines on every send raised engagement on the remaining list over the following quarter. Results vary by list, industry and sending history.
Email measurement should fit your wider content strategy and analytics. For ecommerce, we recommend Shopify, where email revenue can be tracked directly.
How can the Emulent team help?
Emulent audits email deliverability, list health and engagement to find why performance dropped, then fixes authentication, list practices, segmentation and reporting. A caveat: some open-rate changes reflect measurement shifts rather than real behavior, so judge progress on clicks, conversions and revenue over several months. Contact the Emulent team to diagnose your email performance.