- Your signup form and checkout opt-in do most of the work. Get those right before you try anything clever.
- Welcome email #1 earned about $4.50 per person across 4 consumable brands, about 30x emails #2 to #5. List growth only pays if that email is ready.
- A bigger list isn't automatically better. Klaviyo email plans are priced by active profiles, so people who never engage cost you money.
- Track signups by source. Quizzes, sampling and in-store signups often bring in fewer people who are more likely to buy.
Why grow your email list at all?
Ads are rented, your list is owned. Every subscriber is someone you can reach again without paying for the click.
And the first email they get matters a lot. Across 4 consumable brands I pulled data on, welcome email #1 earned about $4.50 per person, compared to about $0.10 each for emails #2 to #5. A wellness brand I work with had a welcome email #1 that made $2,160 from 50 deliveries in one month, about $43 every time it was sent.
So list growth and your welcome flow are the same project. More on that in the welcome email series.
Where do email signups come from?
For most Shopify brands, signups come from a handful of places:
- Signup forms on your site (popups, flyouts, embedded forms)
- The offer on those forms
- Product quizzes
- The marketing opt-in at checkout
- Sampling, in-store and packaging
- Content and back-in-stock signups
1. Signup forms: popups, flyouts and embedded forms
Your popup is probably your biggest source of new subscribers, so give it real attention.
Klaviyo's help center lists five form types: popup, flyout, full page, embed and banner. A few features worth using:
- Teasers let people reopen a popup they closed. They work with popups, flyouts and full page forms, not banners.
- Multi-step forms split fields across pages. A common setup asks for email first, then phone number on step two.
- Targeting and display rules control timing, frequency, device and audience. Klaviyo also supports showing a popup when someone is about to leave the page.
- Different mobile and desktop versions. Klaviyo lets you show different content on each, which matters because most of your traffic is probably on a phone.
One thing to know if you collect phone numbers: Klaviyo says adding a phone number field collects promotional SMS consent by default. Make sure your form's consent language covers that.
Once your form is live, the number to watch is how many visitors actually sign up. I go into that in signup form conversion rate.
2. The offer on your popup
The offer decides who signs up. A big discount gets you a lot of people who want the discount. A smaller offer, or a reason to join that isn't a discount, gets you fewer people who want the product.
So test it. Klaviyo lets you A/B test sign-up form offers: build two versions of a form, for example 10% off vs free shipping, tag each with a hidden property, and send each group a welcome email with the matching offer.
What to offer, and when a discount is worth it, is in email popup discount. The bigger picture on discounts is in my email discount strategy.
3. Product quizzes
For skincare, supplements, haircare and other "which one is right for me?" products, a quiz can be one of the best signup sources you have. People answer a few questions, then give their email to see their result.
The real value is what you learn. Someone who tells you their skin type or their goal can get a welcome email built around that answer, not a generic one. Most brands use a quiz app that sends the answers into Klaviyo as profile properties.
How to set one up, and what to ask, is in product quiz email capture.
4. The marketing opt-in at checkout
Everyone who checks out gives you their email. Not all of them agree to marketing. The checkbox at checkout is how you ask.
In Shopify, you turn it on under Settings > Checkout, in the Marketing opt-in section. Shopify's help center says you can choose whether the box is preselected and in which regions, or let Shopify preselect it based on local rules. The same setting covers customers signing into their account. Check the rules where your customers live before you preselect anything.
It's easy to forget because it's a setting, but it catches people who skipped your popup and bought anyway.
5. Sampling, in-store and packaging
If your product is sold in stores, handed out at events or shipped in a box, every one of those is a chance to get an email.
Klaviyo Academy has a guide on using QR codes for this. The idea: build a mobile-friendly signup form that only shows on the page the QR code links to, and put the code on posters, in shop windows, on business cards and on packaging. A hidden Source field tracks where each signup came from, so your welcome flow can split in-store subscribers into their own path with a different offer.
A few places I'd put a code:
- Sampling and events. Someone who just tasted your product is about as warm as it gets.
- Retail displays. Especially right after a retail launch. More on that in email marketing for a retail launch.
- Inside your box. This catches people who got your product as a gift and aren't on your list yet.
Klaviyo's guide is clear on one thing: don't put a QR code up without context. Say what people are signing up for, and link your terms and privacy policy.
6. Content and back-in-stock signups
Some people will join for something useful, like recipes or a routine guide, before they're ready to buy. Content warms people up. Just make sure the emails that follow still give them a reason to buy.
And don't forget back-in-stock signups. When a product sells out, the "notify me" button on the product page is a signup form full of people who already want the thing. A snack brand I work with had its back-in-stock emails earn about 1.7x its average per person. More in Klaviyo back in stock emails.
How do you know your list growth is working?
Not by list size. Track these instead:
- Signups per week, by source. If you don't know where your subscribers came from, you can't tell which source is worth more effort.
- Welcome email #1 revenue per person, by source. A source that brings in half as many people who buy twice as often is the better source.
- How many new subscribers become customers. That's the number that matters.
- Engagement over time. A fitness tech brand I work with earned $0.19 per person from an engaged segment of 7,145 people, compared to $0.04 per person from a full-list blast to 49,475. A big list of people who don't engage is mostly a bigger bill.
That last part is real money. Klaviyo email plans are priced by active profiles, and if you go over your plan's limit, it upgrades to the next tier. Growth that brings in people who never engage costs you twice: once on the bill and once on deliverability. A sunset flow keeps that in check.
Where these numbers come from
The welcome email numbers come from 4 consumable brands I work with: 2,897 campaigns and $17.7M in email revenue. It's a small sample, so read it as directional. Single-brand numbers are from individual client accounts.
FAQ
What's the fastest way to grow an email list for a Shopify store?
Fix your popup first: the offer, the timing and the mobile version. Then turn on the marketing opt-in at checkout. Those two usually do more than any new channel.
Should I offer a discount for email signups?
Often, yes, for a first order. But test it. A big discount brings in discount hunters. Klaviyo lets you A/B test sign-up form offers, like 10% off vs free shipping, so you can see which one brings in buyers.
Do product quizzes really help with email capture?
For products where people aren't sure which one to pick, like skincare or supplements, they can. The bigger win is what you learn: you can send a welcome email based on their answers.
How do I collect emails in a retail store?
Use a QR code that goes to a mobile signup form, with clear consent language. Tag those signups with a source so your welcome flow can treat them differently.
Is a bigger email list always better?
No. Klaviyo charges by active profiles, and people who never engage drag down your results. A smaller list of people who open, click and buy is worth more.
Founder of Bardown Digital, a Chicago-based Klaviyo email and retention agency for Shopify brands. He's worked with brands doing $500K to $100M a year, with $100M+ in email-attributed revenue across them.