So far in this series, we’ve covered domain authentication and domain warming, the two settings that determine whether your emails reach the inbox at all. You can catch up on those here: Domain Authentication Explained and Domain Warming Strategy.
This week is about what happens after your emails land. You’re getting delivered, but your open rate is still lower than you’d like. Here’s how to actually figure out why, instead of guessing.
Before we go further, a quick note. Open rate as a number is not perfectly reliable to begin with. Apple’s Mail Privacy Protection and similar settings can inflate the number, and some genuine opens never get counted either. If you want the full explanation of why the raw number can mislead you, I wrote about that here: Why Your Email Open Rates Might Be Lying to You. For this post, we’re assuming your open rate is genuinely low, not just misreported, and looking at what causes that and what to do about it.
First, rule out delivery
Before assuming the problem is your content, go back to the first two things in this series. If your domain isn’t fully authenticated, or if you recently changed domains or went quiet and skipped the warming process, a chunk of your emails may never be reaching the inbox at all.
That shows up looking exactly like a low open rate, except the real cause is delivery, not engagement. Check those two things first. There’s no point in troubleshooting subject lines if half your list never sees the email.
The full list of what can cause a low open rate
Once delivery is confirmed, a genuinely low open rate usually comes down to one or more of the following. Some of these are things you control directly. Others are shifts happening across the entire email industry right now, worth knowing about so you don’t blame yourself for something outside your control.
- Subject lines that don’t earn attention.
The most obvious cause, and the one people fix first, often without much effect, because it’s rarely the whole story.
- An audience that’s stopped recognizing you.
Inconsistent sending means subscribers may not remember signing up, or may not connect your name to anything specific. Recognition is a big part of what gets an email opened.
- A list that’s aged out.
Email addresses go stale over time, even without a single unsubscribe. People change jobs, abandon old inboxes, or quietly lose interest. A list that hasn’t been cleaned in a while drags the average down, even if your most engaged subscribers are opening every time.
- Tab placement, not spam.
If a large portion of your list is on Gmail, your emails may be landing correctly in the Promotions tab rather than spam or the primary inbox. That’s not a deliverability failure, but many people check that tab less often, so it quietly suppresses opens without anything technically going wrong.
- Focused Inbox on Outlook and Microsoft addresses.
Microsoft splits inboxes into Focused and Other, and newsletters routinely land in Other, a tab many subscribers rarely open. If a chunk of your list uses Outlook, Hotmail, or Live addresses, this can explain a consistently lower open rate on that segment specifically.
- Apple Mail Privacy Protection.
Since 2021, Apple has preloaded tracking pixels for many Apple Mail users, which can inflate reported opens whether or not someone actually read the email. Apple adjusted how this works in 2024, and reported opens have shifted since, sometimes down, even when real engagement hasn’t changed. This one cuts both ways; it can make your number look better or worse than reality depending on when your list picked up Apple users.
- Image blocking.
Since open tracking depends on a small image loading, any email client that blocks images by default will never register that open, even if the email was fully read. This affects a meaningful share of inboxes and isn’t something you can fix from your end.
- Engagement dilution.
If your list has grown recently but the new subscribers are less engaged than your original core, your overall open rate can drop even though your best subscribers are still opening consistently. This is worth knowing so a dip doesn’t automatically read as a problem with your content.
- Sending frequency.
Both directions cause trouble. Sending too rarely means people forget who you are. Sending too often causes fatigue, and fatigue shows up as declining opens over time even among people who used to engage reliably.
- Send timing.
Worth checking, though usually a smaller factor than the others. Flodesk’s analytics show you exactly when your subscribers tend to open, which is more useful than a general best practices guideline.
- Small list size.
If your list is on the smaller side, individual sends can swing several percentage points just from normal variation. A single low open rate on a small list is not necessarily a pattern yet, it might just be a handful of people.
How to check which one applies to you, step by step
This is where most people stop too early. Flodesk actually gives you enough data to narrow this down fairly precisely, if you know where to look.
Start with the account-level view
Go to Analytics in the top navigation, then Emails. This dashboard covers all of your regular campaign sends. At the top, the lifetime email metrics card gives you your overall open and click rate. Scroll down to the Performance by email table, which lists every email you’ve sent side by side with its own open and click rate. Sort this table by open rate to see your highest and lowest performing sends in one place.
Look for a pattern, not a single number
Are your low performers spread randomly across topics and dates, which points more toward subject lines or list fatigue, or are they clustered, all sent around the same time, all on the same topic, all right after a quiet stretch, which points toward something more structural like list disengagement or a gap in sending.
Check your send time patterns
Still on the Emails analytics page, use the Best days to send heat map and the When subscribers open your emails heat map. Both let you filter by time period, so you’re seeing patterns specific to your actual audience, not a generic industry recommendation.
Check device and client patterns
The Clicks by device type chart shows your desktop versus mobile split. It won’t tell you about Gmail tabs or Outlook’s Focused inbox directly, but a heavily mobile audience with low opens is worth cross checking against subject line length and preview text, since those get cut off differently across devices.
Drill into a specific underperforming email
Go to your Emails list, hover over any sent email, and click View Results. This shows you sent versus delivered versus opened for that specific send. If delivered is high but opened is low, that’s a genuine engagement problem on that email specifically, not a delivery issue. Use the view selector in this report to filter for subscribers who didn’t open, and look at who they are. If it’s mostly subscribers who joined a long time ago, that points to list aging. If it’s a broad mix of old and new subscribers, that points more toward subject line or timing.
Check your list health separately
Go to Analytics, then Subscribers. The Performance by segment table shows engagement broken down by segment, useful if you’ve segmented by engagement level or interest. The Performance by subscriber table shows individual engagement data for each subscriber and lets you sort by any column, including opens and clicks. Sort it to find the subscribers with the lowest engagement across your sends. If a large portion of your list shows little to no activity there, that’s a strong sign your active list includes a lot of dead weight, and it’s worth cross referencing against how long ago each of those subscribers joined.
Use resend to unopens as a diagnostic, not just a tactic
From the three dot menu on any sent email, Resend to unopens lets you send the same email again, with a different subject line, only to people who didn’t open the first time. Beyond the extra opens it can generate, it’s a useful test. If the resend performs noticeably better with a new subject line, that’s a strong signal your original subject line was the main issue. If the resend also underperforms, the issue is more likely list health or delivery than the subject line.
Why this matters before Q4
A low open rate in July is a much easier problem to diagnose and fix than the same problem in November, when you’re relying on your list to actually see your Black Friday emails. If your open rates are already underperforming now, that’s worth understanding and addressing while the stakes are lower, not during your highest-volume sending period of the year.
Want a second set of eyes on your numbers?
Reading your own analytics objectively is hard, especially when you’re close to the content. If you want help figuring out what’s actually going on with your open rates, and a clear plan for what to do about it before your busiest season starts, that’s something we can go through together in a 1:1 consultation session, or address more thoroughly as part of a Migration and Setup project if there’s a bigger cleanup involved.
This is post three in Your Summer Email Tune Up. Catch up on domain authentication and domain warming if you missed them.
