Mailchimp’s Bot Filtering Meltdown
Open rates gone mad? Here’s what’s really going on, and what you need to do next
You’re not imagining things.
If your Mailchimp open and click rates have dropped off a cliff recently, you’re not alone.
And no, you haven’t broken your list or suddenly been blacklisted.
What’s actually happening is a classic case of platform panic, made worse by a lack of communication from Mailchimp HQ.
On this page, we’ll break down what’s happened and – more importantly – show you how to take back control.
Sorry, but your old open rates were lying to you
Before this update, Mailchimp (and most email platforms) were reporting massively inflated open rates, for a couple of reasons:
Reason #1: Apple’s Mail Privacy Protection (MPP). When someone with Apple Mail received your email, it was automatically “opened” by Apple’s servers, before the human ever saw it (if they ever did at all). That counted as an open. Not particularly helpful for anyone who wants actual real humans to see the marketing messages they’ve carefully crafted.
Reason #2: Security bots & firewalls. Especially common in B2B settings (schools and corporates in particular), these bots scan emails for threats by opening them and clicking on links. Again, long before a person gets near it.
All of this means that many “opens” were never actually real. You weren’t always getting a 45% open rate, you were getting 45% reported opens, with a big chunk of that being tech, not people.
What Mailchimp’s done to reduce (and confuse!) the open rate problem
So, at the back end of 2025, Mailchimp quietly rolled out a new bot filtering system designed to strip out inflated opens and clicks caused by Apple Mail Privacy Protection and security bots. The aim? Give users a more accurate picture of real human engagement?
(The reality? They’ve gone a bit too far.)
Sure, the underlying problem they’re trying to solve is definitely legit. But from what we (and a lot of other people) can tell, Mailchimp’s new bot filtering is currently a little too aggressive to actually do the job.
The result? Open and click rates have plummeted so low and so inaccurately that who knows what on earth we can believe right now.
How do we know the Mailchimp’s open rate filtering is off base?
Pretty simple really: because the numbers don’t add up, and we’re not the only ones seeing it.
Since Mailchimp’s new bot filtering kicked in, reported open and click rates have fallen off a cliff. But when we look at actual performance data, like UTM-tracked links, Google Analytics sessions, website hits, and most importantly, sales, nothing’s changed.
We’re still seeing the same flow of traffic, the same engagement, and in some cases, the same conversion volumes from email. The only thing that’s different? Mailchimp says it isn’t happening. A quick scroll on Reddit tells us we’re not alone either:
“Our emails went from 30–50% engagement to under 5%, and that’s just not possible — our local, loyal customer base hasn’t changed.”
– Reddit user
“Click rates now show 0%, but Google Analytics is still showing the same volume of hits from email links. That’s not just off — that’s broken.”
– Reddit user
“Bot filtering is filtering actual customers — we’ve cross-checked it with other behaviour and sales. Mailchimp is throwing the baby out with the bathwater.”
– Reddit user
“The bot filtering is WAAAAY too aggressive. It was filtering nearly 95% of users. Many of them were actual people engaging in other ways.”
– Reddit user
To us, it looks like Mailchimp’s filtering system is currently too blunt, labelling real people as bots and stripping them out of your reporting.
So if your latest campaign shows a click rate of 0%, don’t panic. Look at your UTM-tracked data. Look at your website hits. Look at what your customers are doing, not just what Mailchimp is showing you. That’s where the truth is hiding.
What businesses need to take away from Mailchimp’s new bot filtering
First off, when you see a marketer promising “65% open rates!”, take a moment and remember that whatever platform they’re using probably hasn’t caught up with the roll-out yet.
Second, remember that open rates don’t really matter (shock horror!!). It’s what happens after the open that you ought to really care about:
Did they click?
Did they buy?
Did they get in touch?
That’s what to track. That’s what to care about. And that’s what’ll grow your businesses.
And thirdly, try not to doubt yourself. Your emails probably haven’t suddenly become terrible. Your subscribers probably haven’t decided to desert you en masse. What’s changed is how Mailchimp is interpreting the data, and what it’s choosing to show you.
Here’s what businesses can (and should) do in response to Mailchimp’s spam filtering rollout:
A quick look at your open rates might feel a bit scary, especially if you were proudly boasting numbers upwards of 30% not so long ago.
But all’s not lost. Email’s still not dead. And here are three steps you should take to remind yourself of that, and to maximise engagement with your email list:
1. Give yourself some reassurance that you’re not actually at panic stations: toggle the bot filtering settings
In your campaign reports, look for:
“Bot filtering on” (green dot): The new system is active.
Or possibly the “Exclude Apple MPP…” checkbox, though that’s on older filtering only.
You can toggle these on/off manually. Doing so will reveal how your numbers compare under both systems. The truth lies somewhere in the middle, so neither number is actually hugely helpful, but toggling will at least give you some indication of whether there’s actually been any significant change in your opens.
2. Clean your email list (and KEEP cleaning it every week)
While you’re here, take the chance to clear the deadwood. Mailchimp offers a simple filter by unsubscribes and cleaned option at the top of your audience, and you should be regularly archiving all of these contacts. But you can also use segmentation to identify other disengaged subscribers and get rid of them too. What do you want them clogging up your subscription contact limit and skewing your open rates even further for?! Here’s a segment I like to create and clear out on the regular on our clients’ behalves:
Joined more than 90 days ago*
Have not opened or clicked ALL of the last 10 / 20 / 50 campaigns
*Adding this filter in first means that anyone who you’ve manually added to your list in the last three months – who probably won’t have received all of the last 10 / 20 / 50 campaigns that have been sent – won’t get chucked out by accident.
Archive those subscribers or run a re-engagement campaign. A clean list means better deliverability and more accurate metrics.
3. Add UTM codes to EVERY email link
This is non-negotiable for tracking now. If you want reliable tracking of which emails actually drive clicks and sales, UTM codes are essential.
Even if Mailchimp under-reports clicks, Google Analytics won’t.
How to Add UTM Codes in Mailchimp:
First, make sure you’ve got the source tracking enabled in your G4 Analytics. There are two ways to install it:
1. Manually copy and paste your G4 tracking code into every webpage you want to track
2. If you’re already using Google Tag Manager, you can create a new Google Analytics: G4A Configuration tag, enter your measurement ID and set it the trigger to work on “All pages” and publish a container.
Then, in Mailchimp, scroll down and enable “Add tracking” on every campaign and then make sure you’re including UTM parameters on every link you add to your emails.
How to create your UTM parameters and keep them consistent:
Use a UTM builder like Google’s Campaign URL Builder
Use consistent naming like: utm_source=email&utm_medium=mailchimp&utm_campaign=january_offer
Keep a record of every UTM tracking link you’ve created for every webpage you want to track in one place
Then, in Google Analytics (or GA4), track real web traffic, sales, and conversions, independent of Mailchimp’s messy data.
Mailchimp open rates drop: the bigger picture for your marketing
Here’s hoping Mailchimp manages to right their wonky reporting before too long. But this somewhat silly shift is a reminder to stop obsessing over open rates. They’ve always been a shaky metric.
Your real metrics are replies, conversions, sales, phone calls, survey completions, bookings – whatever end result you’re looking for that’ll turn into cash in your business’s bank.
Mailchimp’s new filtering is flawed, yes, but it’s also a chance to reset your perspective. Measure what actually moves the needle in your business.
And the more you can control your own tracking? The less you’ll be at the mercy of panicked platform updates.
Need help implementing this?
If you’re ready to get clear data and real results from your email marketing, book a free Business Growth Call with our team here:
Get help to grow your business, for FREE
Book a free 3XM Business Growth Call, and spend 30 minutes with a member of the 3XM team, where we’ll help you outline some straightforward actionable things you can do to improve your marketing and grow your business, no strings, no tie ins, and no purchase necessary.
During your Business Growth Call, we’ll:
- Take a look at the marketing you’re doing, and give you our two cents on how to improve it
- Tell you what we’d be doing if we were in your shoes
- Give you actionable tactics and strategies we’re using right now to get leads and customers for our clients
- Make sure you walk away with something you can take away and use straight away
Click the button below to book a slot, and we’ll see you on the call:
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Let’s get your emails working harder, and more honestly.
What’s happened to Mailchimp’s email reporting? The short version!
Your old Mailchimp were never totally accurate. They were bloated by:
• Apple’s MPP pre-fetching (emails marked “opened” without a human ever seeing them)
• Security bots testing links before human delivery
• Firewalls mimicking engagement
Mailchimp’s update tries to correct this… but it’s gone too far. Until they refine their filtering, expect inaccurate and wildly under-reported numbers.
What should you do?
• Toggle bot filtering on/off to compare data (if there’s no drop, the likelihood is that your traffic and results will have remained largely the same too)
• Segment and clean your list regularly to improve open rates (if you care about that sort of thing!) and deliverability (you definitely SHOULD care about that!)
• Track every campaign using UTM codes
• Focus on real-world outcomes, not just opens
• Use Google Analytics to verify your performance
• Ask for help if you need it (you know where to find us)
