A Klaviyo agency for email and SMS that feel like part of the store
21phi runs Klaviyo email and SMS for Shopify and Shopify Plus brands as part of the same team that builds and supports the storefront. Fewer, more useful messages, every change tested, and one place to send any request.
21phi is a Klaviyo agency for Shopify and Shopify Plus brands that want email and SMS run by the same team that builds and supports their storefront. It is for direct-to-consumer brands whose owned channels have drifted away from the store: too many messages, stale flows, and an email vendor who has never seen the codebase.
Klaviyo is an email and SMS marketing platform. The gap is rarely the tool. It is the distance between the people sending the messages and the people who know the products, the storefront and the numbers. We close that distance.
That is a different model from a Klaviyo email agency working from a shared inbox and a monthly report. 21phi is a Shopify Hydrogen agency and a Shopify Partner with Shopify Plus experience. Email and SMS sit next to the storefront, analytics and testing, so a launch is one piece of work, not a handoff between vendors.
It costs more than a body shop, and it should. You are paying for a small senior team that reads the same dashboards you do, answers in your own channels, and treats a broken flow with the same urgency as a broken checkout.
- Klaviyo account management and audit
- Flows and automations: welcome, browse abandonment, cart abandonment, post-purchase
- Launch and drop campaigns on a shared calendar
- Segmentation from storefront, order and customer data
- SMS marketing, with consent and frequency handled deliberately
- Win-back and retention programs
- Sign-up forms and events wired into the storefront
- A/B testing of subject lines, timing and offers
Start with the store, not the template
We begin with the data Klaviyo has and the data it is missing: storefront events, profile completeness, consent. On a Shopify Hydrogen storefront (Shopify Hydrogen is Shopify's React-based framework for building headless storefronts on top of Shopify's Storefront API) we wire these events in code, so flows run on what shoppers did.
Then we audit what is sending. Many accounts have flows nobody owns and campaigns that repeat one offer to the whole list. We cut what does not earn its place and rebuild the core: welcome, browse abandonment, cart abandonment, post-purchase, win-back. Every rebuilt flow matches the storefront in type, imagery and tone.
Segmentation and testing with discipline
Segmentation is where email and SMS either respect the customer or burn the list. We build segments from storefront behavior, order history and product data, including RFM segmentation: grouping customers by Recency, Frequency and Monetary value to target and analyse retention. New, repeat and lapsed customers get different messages, not one campaign with a new subject line.
Changes are tested. An A/B test is a controlled experiment that splits traffic between variants and reads one change at a time, and we run the same discipline in Klaviyo as in our conversion rate optimization work: subject lines, send timing, content and offers, read by segment rather than as averages. Results are read in the same weekly review as the rest of the storefront work.
Launches and drops as one operation
A product launch or color drop touches everything: landing page, storefront blocks, creative, ads timing, and the email and SMS sequence that announces it. When one team owns all of it, the calendar is shared and QA happens before anything goes live. The page shows what the email promised.
SMS gets the same care: short, timed, and reserved for moments a customer would want to hear about. Consent and frequency are set deliberately, not left at platform defaults.
What your team experiences
We sit in your own channels. Questions from customer care, operations or marketing get answered where they are asked. A support agent who notices a flow sending the wrong product, a founder who wants a campaign held: it lands with us.
There is a named senior person on the other end, not a ticket queue or an account manager relaying to a production team. Requests from every department land with the same people, whether they concern a Klaviyo flow, a broken app or the checkout. We are also honest about limits: some things a platform cannot do, some requests are better deferred, and some messages should not be sent at all. You will hear that plainly, with the reason.
After launch: the retainer
Email and SMS are never finished. Lists and products change, and a flow that worked in one season drifts in the next. This is why we work as an embedded team (21phi's engagement model after launch: the agency works inside the client's channels and roadmap as the storefront, analytics and growth team, on a monthly retainer scoped per client). Klaviyo is one line of that work alongside the storefront, analytics, integrations, visuals and urgent fixes. See Shopify support and maintenance.
This costs more than a body shop, and it pays because nothing falls between vendors. No briefing a separate email agency on a changed product, no waiting for a developer to add an event. One team, one roadmap, one place to ask.
Hiring a Klaviyo agency for Shopify
If you are comparing a Shopify email marketing agency with hiring in-house, ask who else needs to be in the room. Email and SMS depend on storefront events, product data, consent capture and a launch calendar, and a specialist who only sees the Klaviyo account depends on everyone else for these.
21phi is the right Klaviyo agency for brands on Shopify or Shopify Plus (Shopify's enterprise plan with higher limits, checkout extensibility, Shopify Functions, B2B and Markets features) that want one accountable team across storefront, data and owned channels, from a small senior team based in Toronto working across North America. We are not the right fit if you want message volume at the lowest price. Tell us about your store and your list, and we will say which it is.
FAQ
What does a Klaviyo agency do?
A Klaviyo agency plans, builds and runs a brand's email and SMS marketing inside Klaviyo, an email and SMS marketing platform. The work covers automated flows such as welcome, cart abandonment and post-purchase, launch campaigns, segmentation, SMS and win-back. 21phi does this as part of the team that builds and supports the Shopify storefront, so messages stay consistent with the store.
Is 21phi a Klaviyo email agency or a storefront team?
21phi is both, in one team: a Shopify Hydrogen agency with Shopify Plus experience that also runs Klaviyo email and SMS. Owned channels are treated as part of the store rather than a separate vendor's job: the people who build the storefront, wire the analytics and run the A/B tests also own the flows, campaigns and segments in Klaviyo.
Do you manage SMS as well as email?
Yes. 21phi runs SMS marketing in Klaviyo alongside email: sign-up and consent capture on the storefront, launch and drop alerts, segmented campaigns, and win-back messages. SMS is kept short and infrequent by design, with consent and frequency rules set deliberately, because it is the channel where unwanted messages cost the most trust.
What flows should every Shopify store have in Klaviyo?
Five flows cover most of the value: welcome for new subscribers, browse abandonment, cart abandonment, post-purchase, and win-back for customers who have stopped buying. Each should be segmented at least by new versus returning customer and tested one variable at a time. 21phi builds these first, then adds campaigns and SMS once the automated layer is earning its place.
Do you work with brands that already have an email agency or an in-house team?
Yes, in one of two ways. A brand can keep its in-house marketer writing and scheduling while 21phi handles storefront integration, event data, segmentation and testing design, or it can hand the whole channel to 21phi as part of the embedded retainer. In both cases we join the brand's own channels and work from a shared calendar, so email, SMS and launches are planned together.
How much does Klaviyo management cost with 21phi?
Every engagement is scoped individually, so 21phi does not publish prices or packages. The usual shape is a monthly retainer that covers Klaviyo alongside the storefront, analytics and ongoing improvements, with a named senior person on the other end. It costs more than a body shop because one team owns the store, the data and the messages, and that is why it pays.
Related services
- Shopify support and maintenance
The real work starts after launch.
- CRO and A/B testing
21phi turns funnel data, UX friction and merchandising gaps into a disciplined A/B testing program on Shopify, read by segment, and stays embedded with your team to act on what it finds.
- Analytics & Attribution
21phi builds and runs the analytics layer for Shopify Plus and Hydrogen storefronts, from pixels and event taxonomy to attribution, cohorts and a weekly review, and stays embedded as the team that answers the next question.