The verdict on email opens? Machine opens have ruined them. They're unreliable. They're meaningless. Or so the story goes.

But here's what no one's telling you: The teams at Yahoo, Microsoft, and Google—the very people building the filters that decide where your emails land—still care deeply about opens. And after analyzing millions of campaigns and sitting down directly with these mailbox providers, we've uncovered something that challenges the conventional wisdom: opens remain one of your most valuable signals for deliverability and performance. 

Let us show you the data that proves it.

The balancing act every email marketer knows too well

You're juggling multiple priorities that all feel equally urgent. On one hand, you're cranking out campaigns to hit your volume goals and drive revenue. On the other, you're carefully monitoring your deliverability to ensure your messages actually reach the inbox. And somewhere in between, you're fielding an endless stream of advice:

• Should you personalize the subject line more? The content? The offer?
• What about Google annotations and schemas? (And wait—what are those, exactly?)
• How are mailbox filters and their AI actually interpreting all your carefully crafted personalization?

These are the right questions to ask. And the answer to "what's working?" comes down to one thing: data.

But that raises another critical question: Which metrics actually tell you what's working?

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Let's talk about healthy deliverability first

Before we dive into the metrics themselves, let's align on what we mean by "healthy deliverability." In the simplest terms, it means that mailbox providers view your brand as a sender who provides value to their recipients. And your messages deserve to land in the inbox, not the spam folder.

So how do you achieve this coveted status? Our Attentive Deliverability Team has sat down directly with the teams at Yahoo, Microsoft, and Google, and they've told us point-blank: send messages to recipients who have shown signs of wanting your messages.

It's that straightforward.

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The four signals of recipient interest

Within email marketing, you have four key metrics that indicate different levels of interest, arranged from weakest to strongest signal:

1. New signups – They've raised their hand to say "yes" to your messages
2. Opens – They're engaging with your content in their inbox
3. Clicks – They're taking action on what you're sending
4. Purchases – They're converting and driving revenue

Now, let's look at what these numbers actually mean for your campaigns.

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The reality check: from 1 million sends to actual conversions

Let's use a round number that's easy to visualize: 1 million opted-in subscribers. We know your list might be larger or smaller, but this gives us a clear benchmark to understand the funnel.

Here's what typically happens when you send a campaign to 1 million recipients (and the range can be dramatic):

At the low end of performance:

• Opens: ~200,000 (20% open rate)
• Clicks: ~388 (0.04% click rate)
• Purchases: ~4 (0.0004% conversion rate)

At the high end of performance:

• Opens: ~500,000 (50% open rate)
• Clicks: ~51,000 (5.1% click rate)
• Purchases: ~8,000+ (0.8%+ conversion rate)

That's a massive difference. That's exactly why we help our senders pay attention to opens, clicks, and purchases together.

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Why we still care about opens (even in the age of machine opens)

Here's the bottom line: mailbox providers care about opens. So we do too.

Two critical reasons opens still matter:

1. Machine opens only happen in the inbox

Whether it's a machine or a human doing the opening, that open pixel only fires if the message lands in the inbox, not the spam folder. This makes opens a valuable signal for inbox placement. If you see a sudden drop from a 50% open rate to 20%, something significant has changed: either the filter stopped letting you in, or your recipients stopped opening. Both scenarios are worth investigating immediately.

2. Clicks alone don't tell the full story

We absolutely look at clicks, they're powerful proof that subscribers are interested in your content. But here's the challenge: click rates for larger volume senders typically hover around 1-3%. If you only looked at clicks, you'd have no signal of interest from 97% of your recipients. Opens might not be perfect, but they're the best metric we have sitting between "clicks" and "messages delivered."

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The data proves it: engagement recency drives results

At Attentive, we've built unique data sets around the variables that mailbox providers pay close attention to—and engagement recency sits at the top of that list. What we discovered reinforces why opens remain a critical metric.

The recency factor

The propensity to engage and purchase from your campaigns has a very high correlation with how recently a recipient opened a previous message from your brand. Here's what that looks like across your 1 million subscriber campaign:

Recipients who last opened 0-7 days ago:

• Highest share of your audience volume
• Highest open rates and ROI
• These are your power users

Recipients who last opened 30-60 days ago:

• Moderate engagement
• Lower open rates and ROI
• Worth re-engaging with targeted content

Recipients who never opened:

• Neither the mailbox filter placed messages in the inbox, nor did the recipient open
• Critical signal that something needs to change
• Consider list hygiene and re-permission campaigns

These buckets show clear patterns: recency of opens directly correlates with ROI.

Machine opens are more common among your best customers

Here's something fascinating we discovered: not all machine opens operate the same way across different recipient groups. Since pre-fetching mail is costly for mailbox providers, they're strategic about when they do it.

The numbers tell the story:

For recipients who opened within the past seven days:

• 87% of opens come from machines
• 13% of opens come from humans
• Over 97% of all machine opens happen in this group
• Translation: Mailbox providers know these recipients want your mail

For recipients who last opened 120+ days ago:

• Less than 50% of opens come from machines
• More than 50% of opens come from humans
• Translation: Mailbox providers want to see what the recipient thinks when engagement likelihood is low

What this means for you:

When you see a high open rate from recipients who haven't engaged in months, you can trust it as a strong positive signal—because it's much more likely to represent human behavior, not machine activity.

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The bottom line

While not all opens are human opens, opens in general provide critical signals about:

• Inbox placement – Your messages are getting through the filters
• Recipient interest – People want to see what you're sending
• Deliverability health – Mailbox providers view you as a trusted sender

The more recent the open, the higher the chance that the recipient's mailbox filter will view your message as "wanted." And the more the filter views your messages as wanted, the more you'll see healthy deliverability and strong engagement from your recipients.

Opens aren't dead. They've evolved. And when you understand how to interpret them alongside your other key metrics, you'll have a much clearer picture of what's actually working in your email program.

Want to learn more about optimizing your email deliverability and engagement strategy? Our Attentive Deliverability Team is here to help you navigate the complexities of modern email marketing.