Most retention conversations start too late. A brand looks at a flat repeat-purchase rate, a welcome flow that converts fine but reaches too few people, a win-back campaign landing on a list that is smaller than it should be, and the instinct is to fix the flows. Better subject lines. Smarter segments. One more message in the sequence.
Sometimes that is the problem. Often it is not. Often the ceiling was set weeks earlier, at checkout, by the customer data you did or did not collect. Every flow you build in Klaviyo runs on that data. If it is thin at the source, no amount of downstream cleverness fully makes up for it.
This is the part most retention guides skip. They tell you which flows to build. They do not tell you that a misconfigured checkout quietly caps how well any of those flows can ever perform. That is the connection worth making.
Your lifecycle data is decided at checkout, not in your ESP
Here is the uncomfortable version. The data you do not collect at checkout is data you cannot segment on, personalize with, or reach people through later. It is not a gap you can backfill after the fact.
If a customer checks out without leaving an email, they are not a slow-to-convert subscriber. They are simply unreachable on your most important channel. If they leave no first name, your “Hi {first_name}” line has nothing to render. If you never asked for a phone number, SMS and WhatsApp are off the table for that person no matter how good your win-back copy is.
None of these are ESP problems. They are checkout problems that only show up later, disguised as weak flow performance.
Contact method: the email-versus-phone trap
Shopify lets you choose how customers identify themselves at checkout. New stores default to email. Older stores sometimes sit on “Phone number or email,” which lets the customer pick. That sounds customer-friendly, and it quietly costs you subscribers.
When a customer can check out with a phone number alone, some will, and you never capture their email address. There is no way to require both email and phone as the contact method in Shopify, so this is a real choice, not a both-and. For an email-first retention program, set the contact method to email. You still collect phone separately (more on that below), but you guarantee that every order hands you the one identifier your email program cannot run without.
First and last name are not just for the shipping label
By default, Shopify does not force a first name. Last name is required, first name is optional. It looks harmless on the order screen. It is not harmless in Klaviyo.
First name is the backbone of the most basic personalization you have: the greeting, the subject line, the “we saved your cart, {first_name}” nudge. When it is missing, your only options are a generic fallback or an awkward blank. Requiring first and last name at checkout means every profile that syncs to Klaviyo arrives personalization-ready. It is a one-time setting that pays off on every send afterward.
Phone: the reconnection channel you are leaving on the table
Email is your workhorse, but it is not your only line to a customer, and it is not always the one that gets through. People change inboxes, route promotions to a tab they never open, or simply go quiet. A phone number is often the only way left to reach a customer who stopped opening emails a year ago.
Shopify collects phone separately from the contact method, through the shipping address phone field, which you can set to optional or required. Once you have it, and once the customer has consented, it becomes an SMS channel in Klaviyo, and now WhatsApp too, which Shopify recently promoted to a first-class channel alongside email and SMS. For reactivating lapsed customers specifically, a channel that is not email is frequently the only thing that still lands.
The opt-in itself: turning a checkbox into subscribers
Capturing an email address at checkout is not the same as having consent to market to it. That is what the marketing opt-in is for, and small choices here move your subscribe rate.
A few things worth setting with intent:
Preselect where you are allowed to. Shopify lets you preselect the email marketing checkbox by region, and the “Regions recommended by Shopify” option keeps that choice aligned with current guidance. The SMS checkbox can never be preselected; that consent always has to be active. In regions with stricter consent rules, keep the email box unchecked and let people opt in themselves. It protects both the list and your sender reputation.
Rewrite the label. The default text just asks people to subscribe. Tell them what they actually get: offers, restock alerts, order updates. A clear value promise converts better than a bare “email me with news.”
Use the newer surfaces. As of 2026, the same marketing opt-in can appear at sign-in and in the account component, not only at checkout. That is more chances to capture a clean opt-in without adding a single step to the purchase itself.
The catch for older stores
Here is the update that ties all of this together. In August 2026, Shopify began surfacing recommended checkout field settings directly in the admin. New stores already use these recommended settings by default. Older stores do not. Their settings do not change unless you go in and apply the recommendations yourself.
And the recommendations are exactly the three levers above: set the contact method to email, require first and last name, and collect the shipping address phone number. If your store has been running for a few years, there is a real chance it is still on the old defaults, silently collecting less than it could on every single order. The fix is a five-minute review in Settings > Checkout. The payoff compounds on every future customer.
Where Klaviyo comes in
None of this matters in isolation. It matters because of what happens after the data lands in Klaviyo.
Checkout consent syncs into Klaviyo automatically, with email and SMS tracked as separate, channel-specific consent on each profile. Keep them on separate lists so that consent maps correctly. First and last name arrive as profile properties your templates can use. Phone becomes a live SMS channel. Every one of those fields is a segmentation input: reachable by email, reachable by SMS, has a first name, repeat buyer, lapsed and worth a win-back.
The richer the checkout, the sharper the segmentation. The thinner the checkout, the more your Klaviyo account is doing impressive work on an incomplete picture. You can build a beautiful win-back flow, but it can only reach the people you have a channel for, and it can only personalize with the fields you captured at the source.
One caveat worth knowing: consent syncs to Klaviyo when a customer subscribes for the first time in Shopify. Historical subscribers usually need to be added deliberately. So fixing the checkout today improves your data from today forward. It does not retroactively repair the customers you have already under-collected, which is one more reason to fix it sooner rather than later.
The bottom line
Retention feels like a downstream problem, so downstream is where most teams look. But the size of your reachable audience, the quality of your personalization, and the range of channels you can win people back on are all decided upstream, at checkout, before a single flow ever fires.
Set the contact method to email so you always capture it. Require first and last name so every profile is personalization-ready. Collect phone so you have a way back to the people email cannot reach. Configure the opt-in deliberately. And if your store is more than a year or two old, check whether you are still on the old defaults, because Shopify will not apply its own recommendations for you. Get the checkout right, and everything you build in Klaviyo has more to work with.
That is the work: making sure the data your retention program depends on actually gets collected in the first place. If you are running on Shopify and Klaviyo and want a second set of eyes on what your checkout is quietly leaving behind, that is exactly the kind of lifecycle groundwork we do.
Need Help? Say Hello!
eCommerce Today gives you direct access to a whole team of Shopify, Email Marketing, SEO, and Marketplace specialists, without the cost and complexity of hiring in-house or juggling multiple agencies.
Why work with eCommerce Today?
- Founded by eCommerce Business Owners – we have built and scaled stores ourselves
- Shopify Plus Partner and Shopify Apps Development Agency
- Klaviyo Platinum Partner
- 35+ Full-Time eCommerce Specialists, no outsourcing, only in-house expertise
- 5.0 Rating on Clutch.co | 4.9 on Shopify Experts Marketplace (100+ reviews)
“We built eCommerce Today to be the team we wish we had when we were running our own stores. Everything we do is focused on real growth, not fluff.”
- Stefan Chiriacescu, CEO