Are Bot Signups Inflating Your Klaviyo List?
Not every new subscriber is a person.
Some of the signups hitting your Klaviyo list are bots: scripts that fill out your form with fake or stolen email addresses. They pad your numbers and quietly damage your deliverability. Most brand owners don't notice until the trouble shows up somewhere else, like real emails landing in spam.
If your list has ever jumped for no reason you can point to, this one's worth a read.
What bot signups actually are
A bot signup is a fake submission to your email form, made by a script instead of a customer. There are a few reasons they happen.
Some bots hammer any open form they find, just because it's there. Some are running stolen email addresses through your form to see which ones work. Some are testing stolen credit cards against a checkout or a form that hands out a discount code. Whatever the reason, the result on your end is the same: a pile of new contacts that aren't real people and will never buy anything.
They go after forms that are easy to abuse. No protection, an instant discount code on signup, nothing to slow them down.
Why a few fake contacts cause real damage
It would be one thing if bot signups just sat there harmlessly. They don't.
Fake addresses bounce, and some are spam traps, addresses mailbox providers use specifically to catch careless senders. A climbing bounce rate and a spam-trap hit both tell Gmail and Outlook you don't know who's on your list.
Bots never open and never click on their own. So when a wave of them lands, your real rates get muddier and a chunk of your "subscribers" are scripts that do nothing. Mailbox providers watch how people treat your mail. When the signals say people aren't interested, they start routing you to spam.
Here's the part that stings. It isn't only the bots' mail that suffers. When your sender reputation drops, your real emails to your real customers start landing in spam too. The bots drag down inbox placement for everyone. If your emails have started missing the inbox, a bloated list is one of the first things to check.
And there's a smaller, more direct cost. Klaviyo bills based on how many profiles you have. Fake contacts mean you're paying to store people who don't exist.
How to spot it
Bot signups leave fingerprints. A few things to look for:
A sudden spike in signups with no campaign, ad, or promotion behind it.
A burst of signups in a short window, often at odd hours.
Email addresses that look wrong: random strings of letters, unfamiliar domains, lots from the same domain, or a run of addresses with a plus sign in them.
Signups from countries you don't sell to or market in.
Bounce rate climbing and open rates dropping right after a growth spike.
The clearest signal lives in your sender reputation. If you've set up Google Postmaster Tools, a reputation drop that lines up with a signup spike tells you most of the story.
How to stop new ones
Klaviyo forms already have bot protection built in. For any form that collects email or SMS leads or uses a coupon, it's on automatically: a CAPTCHA appears only for visitors showing suspicious or previous bot activity from their IP, and Klaviyo runs a List Bombing IP Management system that flags or blocks IPs firing a lot of submissions in a short window. So the first move is simple: make sure you're on Klaviyo's native forms and haven't switched anything off.
If you run a custom, non-Klaviyo form, you don't get that automatically. Klaviyo recommends adding a honeypot field, a hidden field real people never see and bots fill in, which also lets you tag and segment the bot profiles afterward. That takes a developer and access to your form's HTML. Site-level tools like Google reCAPTCHA or Cloudflare Turnstile do a similar job. All of this lives on your site, not inside Klaviyo.
Double opt-in is the heavy lever, and I'd hold it for when you actually have a problem. With double opt-in, a subscriber only joins your list after clicking a confirmation link, and bots almost never confirm, so an active attack mostly dries up. The tradeoff is real: you also lose some genuine subscribers who never get around to confirming. For most brands on a healthy list, single opt-in is fine. But in the middle of an attack, double opt-in is one of the fastest ways to shut it down, then you can switch back once it passes.
The Shopify side
If your Klaviyo is synced to Shopify, and it usually is, those fake profiles don't just sit in Klaviyo. They flow into Shopify as customer records too, so a real cleanup means removing them in both places, not one.
Bots can also target your Shopify forms and checkout directly, not only your Klaviyo form. If the junk is coming in through Shopify, that's where the protection needs to go, whether that's Shopify's own checkout protections or a bot-detection app for your store. Worth checking where the signups are actually entering before you decide where to fix it.
Bots don't only pad your list, they fake your numbers
There's a second kind of inflation, and it's sneakier, because it makes your email look like it's working better than it is.
Bot clicks. Plenty of inbox providers and corporate security systems click every link in an email before it ever reaches a person, just to check the links are safe. Klaviyo logs these as bot clicks. They make a profile look active when no human did anything, which inflates your click rate and can pull dead contacts into Klaviyo flows meant for real people. Klaviyo lets you filter them out: under Settings, then Attribution, you can exclude bot clicks from your reporting and attribution for email and SMS. Turn it on so your numbers reflect actual people.
One caution here. A real customer behind a strict corporate or Gmail security scanner can get logged as a bot click too. So use the setting to clean up your reporting, but don't go deleting every profile that ever registered one. You'd cut real buyers out of your email for good.
Apple Mail Privacy Protection. If someone uses Apple Mail with MPP turned on, Apple quietly opens your email and loads the images, including Klaviyo's open-tracking pixel, whether or not the person ever looked at it. That logs an open that didn't really happen. For a list with a lot of Apple Mail users, your open rate is partly fiction. Klaviyo gives you an Exclude Apple MPP option in those same Attribution settings, which cleans up your reports.
So here's the move that matters most. Opens are no longer a reliable sign that a real human did anything. Clicks still are. Build the segment you treat as your active subscribers on clicks, not opens. Something like:
Clicked email at least once in the last 90 days.
Set that up in the segment builder under what someone has done, and pair it with the bot-click exclusion switched on, so the clicks you're counting are human clicks. That gives you an honest read on who's actually paying attention, instead of a big "opened in the last 30 days" number that MPP has puffed up.
How to clean up what's already there
If bots are already on your list, switching on protection stops new ones but doesn't remove the old. You'll want to find the suspected fakes and get them off your active list.
Build a segment that catches them by what they have in common: profiles that have never opened or clicked, that bounced, that signed up in a suspicious window, that share an odd domain or a plus sign in the address. Review it, then suppress or delete the ones that are clearly not real, in Klaviyo and in Shopify if they synced through. Don't leave them sitting there. Every send to them keeps the bounce rate up and the reputation down.
If your list is badly inflated and your inbox placement has already slipped, this is the heart of a deliverability and list-health cleanup, and it's worth doing properly before you send another campaign.
When this isn't your problem
Not every brand has a bot problem. If your list grows at a pace you recognize, your bounce rate is low, and your email reaches the inbox, you probably don't need to go hunting. Make sure your Klaviyo forms have their default protection in place, switch on the bot-click exclusion, and carry on.
But if you've seen an unexplained spike, or your open and click rates and inbox placement slipped without an obvious cause, your list is the place to look first.
A quick bot check, list and numbers
Did your list grow in a way you can actually explain?
Is your bounce rate low and steady, not climbing?
Do new signups have normal-looking email addresses?
Are you on Klaviyo's native forms, with their default bot protection in place?
Is "exclude bot clicks" switched on in your Attribution settings?
Are you judging who's active by clicks, not opens, now that Apple MPP inflates opens?
If you've been hit by an attack, have you turned on double opt-in until it passes?
Bots make your numbers look bigger and your email work worse. Catching them is some of the highest-value list work you can do, because a clean list of real people protects every email you send after it.
If your list growth looks off and you want a clear read on what's real and what's not, book a free call. We'll talk through what's going on with your list and whether working together makes sense. No pressure, no pitch.
Email is a system, not a send.
— Alex
Need help implementing these strategies in your email marketing program?
Frequently asked questions
What are bot signups in Klaviyo?
Fake submissions to your email signup form made by scripts instead of real customers. They fill your list with invalid or stolen addresses that never open, click, or buy. Some are testing stolen emails or credit cards; some just hammer any unprotected form they find.
How do I stop bots from signing up on my Klaviyo form?
Klaviyo's native forms already include bot protection: an automatic CAPTCHA for suspicious visitors and a List Bombing IP Management system, both on by default for forms that collect email or SMS or use a coupon. If you run a custom form, add a honeypot field or a site-level tool like reCAPTCHA, which takes a developer. And if you're under an active attack, switching your list to double opt-in shuts most of it down, since bots rarely click a confirmation link. Double opt-in costs you a few real subscribers too, so reserve it for when you need it.
Do bots affect my open and click rates too?
Yes. Security systems and inbox providers click links to check they're safe, and Klaviyo logs these as bot clicks, which inflate your click rate. Apple Mail Privacy Protection auto-opens emails and inflates your open rate. You can exclude both under Settings, then Attribution. Because opens are no longer reliable, judge who's active by clicks, not opens.