What Is Happening to My Open Rates?

If you follow industry email deliverability channels or are tuned in to recent delivery discussions, you’ll know that since April, declining ‘open rates’ have been a hot topic. 

From this time, senders of all sizes have witnessed to varying degrees a decrease in their open rates, even when little has changed with their email program. In turn, this has caused alarm as many still use opens as a KPI or have financial incentives tied to them, even though it’s a dated and unreliable metric.

Of course, we all know there’s a myriad of reasons why open rates can fluctuate. Email senders, email service providers (ESPs), and mailbox providers (MBPs) all have a role in email deliverability, and can all have an impact on whether an email is opened.

This write-up serves to help better understand:

• What is an ‘open’?

• What are the different kinds of opens?

• What is pre-fetching? 

• What are the different types of non-opens? 

• What has changed with the MBPs? 

• What MBPs have impacted open rates the most?

• What else is the industry seeing?  

What is an ‘open’? 

Tracking an "open" in an email involves embedding a tiny, invisible image (often a 1x1 pixel) called a tracking pixel within the email. This pixel contains data about the sender and receiver, along with other metadata. When the email is opened (or fetched), the tracking pixel is loaded from the server, which registers and records the open event. 

But not all opens are the same.

What are the different kinds of opens?

If you see a registered open (fetched image) it could mean any number of things. A colleague of mine, Steve Atkins from Word to the Wise put together a nice list of some of the possibilities:

• The user opened the email in their mail client and read it

• The user’s mailbox provider or mail client prefetched the image because it expected the user to see it, and the user later read it

• The user’s mailbox provider or mail client prefetched the image because it expected the user to see it, and the user didn’t read it

• The user’s mailbox provider or mail client fetches all images as a privacy feature, explicitly so you can’t tell whether the user read it or not

• The user’s mailbox provider or mail client fetches all images not previously categorized as spam, at some random time after delivery, explicitly so you can’t tell whether the user read it or not

• A spam/malware filter somewhere along the delivery path fetched the image so it could make decisions based on the content

• A spam/malware filter at the MX fetched the image during the delivery process, then accepts, defers, or rejects the mail – so you may see an image load hours before the mail is successfully delivered, or even if it was rejected

• The user’s mailbox provider shared the URL of the image with a search engine, and the search engine crawled it (yes, this happens).

• The user previously read the email on a mail client that didn’t fetch images but then, possibly hours later, reads it again on their ‘phone that does fetch images – so you may see click activity from a recipient hours or days before the first “open” happens

• The user configured their mail client not to load images by default, but later chose to fetch them – again, you may see other activity before the first “open”

So, as you can see, opens aren’t as simple as one might think, especially in the age of pre-fetching.  

What is pre-fetching? 

Pre-fetching images is a process used by many mailbox providers to improve user experience, reduce server load, and allow for early content filtering and security scanning. It allows for MBPs and security vendors to look at images and assign risk before delivering the message to the end-user. However, the downside to pre-fetching is that it can artificially inflate open rates and return inaccurate ‘open’ data to the sender. 

What are the different types of non-opens? 

On the flip side, if an image isn’t loaded, and an open is not recorded, that could mean a number of things as well:

• The mail was never delivered

• The mail was delivered to the spam folder so the user never saw it

• The user saw the mail in their inbox but decided not to open it

• The user uses a mail client that doesn’t support linked images (rare on the modern desktop, but not that unusual in some ticketing systems)

• The image was stripped by content filters before delivery

• The user configured their mail client not to load images, but still opened and read your mail

• The user configured their mail client to load images “privately” using, for example, Apple’s Mail Privacy Protection, but they’re also running a corporate VPN client that sometimes breaks that functionality, so the image failed to load

• The email was over 102k long, so it was truncated at Gmail, cutting off the tracking pixel put at the bottom of the email – the user did read the email, but didn’t click the link to load the entire content (beehiiv places their pixels at the top of the email, so this is not an issue)

• The user’s mail client loads images lazily, and they didn’t scroll to the bottom of the long email, so the image was never fetched

• The user fetched the mail to their ‘phone, then later read it on a plane or a train or somewhere else without network connectivity, so the image wasn’t loaded

Like opens, there are a host of scenarios for non-opens as well, many again causing inaccurate numbers.

Pro Tip: While using open rates as an indicator of potential deliverability problems is a valuable pursuit, it’s ill-advised to place significant importance on them or connect financial liabilities to the metric. As well, calculations for opens and open rates are still very inconsistent across the industry, which makes comparing ESPs to one another a difficult task.  

What has changed with the MBPs? 

The email channel is evolving faster today than at any time in our history. New standards, ever-changing technology, and relentless threat actors are all influencing the way mailbox providers look at their inbound email traffic. Today, mailbox providers utilize machine learning, complex filtering algorithms, and third-party data feeds to determine email placement. They also utilize tools like image pre-fetching to help protect their users. 

As we all know, in Sept. of 2020 Apple launched its version of pre-fetching with their Mail Privacy Protection (MPP) feature, which was designed to increase the privacy of their users. The most disruptive aspect of MPP was that it flooded email service providers with auto-generated opens to obscure when and whether Apple Mail users opened emails. This made open rates much more difficult to calculate.

Fast-forward to the Fall of 2023 when both Google and Yahoo announced sweeping security initiatives designed to keep mailboxes safer and free from unwanted mail. 

In short, they focused on a handful of things, including authentication requirements, that were previously best practice recommendations and turned them into requirements that senders must implement. As you can imagine, when two of the largest mailbox providers in the world make changes, there’s certainly a ripple effect.  

These changes were slowly rolled out in February of this year, and the impact was felt in earnest beginning in late March and early April. Around this same time other mailbox providers, including Microsoft, Apple, and Comcast, used the opportunity to make their own filtering changes to better align with these new industry practices. In short, MBPs started making it harder to deliver mail to the inbox.    

As a result, ESPs and the sending community as a whole have witnessed a direct impact on deliverability metrics, including higher volumes of mail sent to the junk folder and lower open rates.  

What MBPs have impacted open rates the most?

As mentioned, many large mailbox providers have had a renewed focus this year on new rulesets and algorithms to thwart unwanted mail. However, in the beginning of April, senders witnessed a pronounced decline in Yahoo/AOL opens. 

This has been attributed to tweaks to their various filtering layers to align with their new security initiatives and a new calculus on when to pre-fetch images. While things have leveled off a bit, open rates at Yahoo/AOL have never really recovered to pre-authentication initiative days, and most feel they never will. Many say this is the “new normal”.     

With Google, most saw a very slow but steady downward trend of opens in the early days of their security initiatives, but nothing crazy. However, recently in July, many ESPs have witnessed a noticeable downward trend. Google, being one of the mailbox providers that perform a lot of pre-fetching, seems to have throttled back on the number of images they prefetch in order to enhance security, which in turn lowers artificially inflated open rates. 

Opens have also recently been impacted by Apple’s private relay outages, taking place in late July.

Why Trust Me: Dave Smith is the Senior Deliverability & Compliance Manager at beehiiv.

What else is the industry seeing?

Another thing that has been noticed is that changing sending identities (authenticated domains, SPF/DKIM/DMARC, new subdomains, or the sending IP address) can trigger Google to stop prefetching images. 

For security reasons, this makes sense, but witnessing lower open rates for some time when warming a new IP or changing any previous sending identities should be expected.

There is also speculation among industry experts that the decline in open rates often correlates with the performance/reputation of the sender and the industry they’re in. 

A few that looked into this data saw that under-performing senders saw a bigger drop in opens (10%-15%) than better-performing senders (0% - 5%), but not everyone saw this phenomenon. Others have commented, and have been witnessed subjectively at beehiiv, that crypto, financial, and other industries frequently associated with phishing/spam have witnessed higher rates of decline. 

Final Thoughts

In recent months, open rates have fluctuated more than ever, even when sender mail programs and ESP platforms haven’t changed.

MBPs, particularly Google and Yahoo, have changed their calculus on pre-fetching images, which has decreased the number of artificial opens. As well, many mailbox providers have tightened their inbound filtering to align with Google/Yahoo’s recent security initiatives. 

As a result, more mail is being diverted to the spam/junk folder. This trend will continue, as recently Microsoft said that it’s not a matter of if, it’s a matter of when they will be following Google/Yahoo’s lead.  

To learn more about the trends for 2024, check out our report here. 

With beehiiv, you can start building your email list today, and not worry about warming up your email list and getting the best 3D analytics to understand how your emails are performing.

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