Email List Building for eCommerce: Popups, Offers and List Quality

A Shopify store grows a list of buyers by timing the popup to interest, making an affordable offer, asking for email before SMS, and welcoming subscribers straight away. Hayes Media, an eCommerce growth agency for DTC and Shopify brands, builds list growth this way and judges it by how many subscribers buy.

What does email list building mean for an eCommerce store?

Email list building is how you turn store visitors into people who've agreed to hear from you by email, SMS, or both. For a Shopify brand, that mostly happens in signup forms: popups, flyouts, and embedded forms in your footer or on landing pages.

List size is how many subscribers you have. List quality is how many of them open, click, and buy. A big list of people who never engage adds sends that earn nothing and, as we cover below, can hurt how inbox providers treat your email. A smaller list of people who wanted your emails means more of every send reaches people who want it, and keeps your sender reputation clean.

So the goal of list building is a list of people who are likely to buy from you.

When should your email popup appear?

Show it when a visitor has had a reason to care, and match the trigger to the page. A shopper on a product page needs a moment to look first. Someone about to leave is your last chance to ask.

Klaviyo sets timing in the Targeting & behavior tab of the form editor. By default, a form shows "Immediately", which Klaviyo says means "it can appear as soon as the visitor meets your targeting and frequency settings." You can also show it based on rules:

Exit intent. Klaviyo describes these as forms that "appear when someone moves their cursor outside the page’s visible area on desktop or scrolls quickly upward on a mobile device."

Time delay. You set how many seconds someone must be on the page first. Klaviyo's own guidance: "As a general rule, visitors usually do not spend more than a few seconds on each page. If your message is crucial, display the form immediately or after 1 or 2 seconds."

Scroll depth. The form shows once a visitor reaches a set point on the page, where "0% is the top of the webpage, whereas 100% is the bottom."

Pages viewed. For example, Klaviyo says that "if you input 3 pages, the form will display when a visitor views 3 unique pages on your website, such as 3 different product pages."

Frequency matters too. For an exit popup, its getting started guide offers settings as "a good place to start": show again after 5 days if closed, don't show again after a submission, and "Don't show to existing Klaviyo profiles" so people already on your list aren't asked again.

Which signup form types should a Shopify store use?

A simple setup is one main popup or flyout plus a footer embed. Klaviyo's getting started guide suggests you "Add an embed form in your footer, in addition to any other popups you publish, to optimize list growth opportunities on your site." Here's how it describes each type:

Popup. "Popups are eye-catching and high converting, but potentially disruptive to a visitor's experience."

Flyout. "Flyouts are still noticeable, but they generally allow a visitor to keep browsing without having to interact with the form."

Embedded form. These sit in a fixed place, like your footer, for visitors who came looking to subscribe. For a footer embed, Klaviyo says "we suggest asking for email consent only to improve the volume of opt-ins."

You can also target forms by URL, UTM parameters, location, device, and list or segment membership, so a discount popup stays off pages where it doesn't belong.

Should your signup offer be a discount?

Only if you're happy to pay that discount on a large share of first orders, and only if your full-price customers are the people it attracts. A discount can bring in more signups. It can also bring in people who signed up for the code and leave once it's used.

Klaviyo's getting started guide treats a discount as optional: "Adding a coupon block to the success step of the form to offer a promotional discount can also further incentivize visitors to opt in and encourage them to make a purchase." It also says that if your form includes an incentive, "new subscribers will expect to be able to use the offer right away." That's why the offer belongs in the first message of your welcome series.

If a percentage off doesn't fit your margins, other offers still give people a reason to sign up: free shipping on the first order, early access to restocks, a gift with the first purchase, or a product quiz. Pick the one your best customers would care about, then test it. Klaviyo suggests you "consider A/B testing your sign-up form offer" to find what works for your audience.

Judge the test on revenue from new subscribers over your normal purchase cycle, as well as signup rate. If an offer wins on signups but brings in fewer orders, it isn't the better offer.

How do you collect email and SMS consent in one form?

Use a multi-step form: email on the first step, phone number on the second, with SMS clearly optional.

Klaviyo explains why: "In general, sign-up forms that collect email consent have higher conversion rates than forms that collect phone numbers." Asking for both at once can slow email growth. With a multi-step form, "If a visitor submits only step 1, you can still collect their email consent and encourage them to subscribe to SMS marketing in the future." Klaviyo calls multi-step forms that collect email and SMS consent on different steps "best practice for list growth and maintaining compliance."

SMS consent has stricter rules than email. From Klaviyo's guide to SMS consent:

Separate consent. "SMS consent also must be collected separately from any other marketing channel." An email signup doesn't give you permission to text someone.

Never make it look required. Klaviyo is direct. Collecting both on the same step "is not recommended, as customers may think they have to sign up for SMS if they want to sign up for email."

Disclosure language. "You should put the disclosure language above the SMS consent checkbox or button."

Double opt-in and bought lists. Klaviyo says double opt-in for SMS is "a carrier requirement in the US for any shopping cart abandonment flow". It also states that "Lead generation, affiliate-related, or purchased lists are not valid SMS consent."

For people already on your email list, Klaviyo's targeting has an option called "Show to email only subscribers", which shows a form to "email subscribers that haven't signed up for your SMS marketing yet." Our guide to SMS marketing for eCommerce covers what to send once they're in.

Why does list quality beat list size?

Because inbox providers decide where your email lands partly from how your subscribers react to it, and people who never wanted your email react badly. Klaviyo's double opt-in guide says most major email clients track how recipients interact with your email, and "They use this information to determine whether your emails are classified as spam." A list full of uninterested people drags down delivery for the people who do want to buy.

Google's email sender guidelines say that "you should send email only to people who want to get messages from you. These recipients are less likely to report your messages as spam." The same page asks senders to "Keep spam rates reported in Postmaster Tools below 0.10% and avoid ever reaching a spam rate of 0.30% or higher."

Without double opt-in, Klaviyo warns, typos get through and "spam-bots could also find your form and flood it with fake email addresses or phone numbers." Its help page adds: "Having a lot of uninterested people or a lot of invalid emails on your list will only hurt your efforts to reach those that actually want to receive your emails."

In practice, list quality comes from decisions you make at signup: an offer that attracts buyers, clear consent, confirmation where it makes sense, and a welcome series that turns a signup into a first order. Our guide to the welcome series email walks through that sequence, and our guide to Klaviyo email flows shows where it sits among your other automations. If someone never engages after that, our article on email unsubscribe rate explains how to read what your list is telling you.

What do good email popups look like?

Here are three popup examples for a made-up store, Harbor Tea Co., which sells loose-leaf tea. The store and the copy are invented to show the mechanism.

Example 1, the first-visit popup. A centered popup on product pages, set to show after the visitor views 2 pages. Step 1 offers free shipping on the first order and has an email field. Step 2 asks for a phone number for restock texts, marked optional, with the SMS disclosure above the button. The offer arrives in the first welcome email.

Example 2, the content flyout. A flyout on blog posts, set to show at 60% scroll. It offers a brewing guide by email and no discount, because these readers are already interested.

Example 3, the exit popup. An exit-intent popup on the cart page that asks for an email to save the cart. It's hidden from existing profiles and waits 5 days after being closed.

A worked example, with made-up numbers: Harbor Tea tests two offers. Form A, 20% off, gets 1,000 signups and 120 first orders from them. Form B, free shipping, gets 700 signups and 140 first orders. Form A grew the list faster. Form B brought in more first orders, 140 against 120, from a smaller list and without giving 20% off each one. Judged on buyers, Form B is the better form.

When does this advice not apply?

If you sell a product people buy once, a big list matters less than a strong post-purchase experience. If you sell in age-gated categories, follow your platform's consent rules for those first: Klaviyo notes extra conditions for age-gated forms. If your traffic is small, there won't be enough signups to read an offer test, so pick one sensible offer and work on traffic. And if you sell outside the US, check the consent rules in each country where you collect phone numbers.

How does Hayes Media build list growth for clients?

Hayes Media builds signup forms, offers, and welcome series as one system, and judges list growth on how many new subscribers become customers.

Hayes Media's retention practice covers email, SMS, loyalty programs, and subscribe-and-save. We work in Klaviyo for most accounts and have experience in most other email and SMS platforms, so a brand on another tool is still a fit. Email on its own is a complete engagement. On email.hayesmedia.co, Hayes says it's "Trusted by 50+ eCom brands" and writes "We grow client lists 3.1x faster." Those figures are published by Hayes on its own site, and Hayes has no third-party review profile and no Klaviyo partner listing, so weigh them as our own account of our work.

We typically work with brands doing at least $100K per month in revenue. It's a guideline, not a gate. A smaller brand with a clear budget set aside to scale and real order volume can still be a fit. One-time email projects start from $2,000 USD, and retainers for ongoing full management start from $4,000 USD per month, scoped on the discovery call. Our email marketing audit guide shows what we check, and the email and SMS service page covers how we run a program.

If your list is growing and your revenue isn't, a discovery call gets you an audit of your signup forms, your offer, your consent setup, and your welcome series, with what to fix first. No onboarding fees. No lock-in contracts. No junior marketers. Book a discovery call

Sources

Klaviyo, Understanding targeting and behavior settings for sign-up forms: https://help.klaviyo.com/hc/en-us/articles/4413544555547

Klaviyo, Getting started with sign-up forms: https://help.klaviyo.com/hc/en-us/articles/360026474752

Klaviyo, Understanding multi-step forms: https://help.klaviyo.com/hc/en-us/articles/4404256496283

Klaviyo, Understanding SMS consent collection: https://help.klaviyo.com/hc/en-us/articles/360035056972

Klaviyo, Understanding the double opt-in process: https://help.klaviyo.com/hc/en-us/articles/115005251108

Google, Email sender guidelines: https://support.google.com/a/answer/81126

Hayes Media retention figures and terms: https://email.hayesmedia.co/