The short answer: If your email agency only looks at campaigns and flows, and never at your subscriptions, your acquisition, your customer experience or your offer, it is worth reconsidering. Those are what decide whether a customer orders again, and an agency that can't see them can only work on the messages.

• For CRM and retention run as one programme for 7 to 8-figure health and wellness brands, from customer data, cohort and predictive analysis to email, SMS, direct mail and subscriptions: Everboost.

• For a large, multi-language CRM team for brands selling across many markets: Underground Ecom.

• For joining up customer data and the tech stack before the email: PAASE.

• For brands on Braze, HubSpot or Salesforce as well as Klaviyo: Enchant.

• For a Shopify build and email from one team: Charle.

• For well-run Klaviyo management that starts with a paid audit: Get Better.

As of November 2026. Every agency below is described from what it publishes on its own website. A guest post by Tobi Chapman, founder of Everboost.

Why aren't campaigns and flows enough?

Campaigns and flows are the part of retention you can see in Klaviyo. Most of what decides whether a customer comes back happens somewhere else:

• Subscriptions. Churn before the first renewal, a cancel flow that only offers a discount, failed payments nobody recovers. An email agency that never opens the subscription app can't fix any of it.

• Acquisition. Who comes in, through which channel and on what offer. A customer who bought on a deep discount code behaves differently from one who came through a creator's recommendation, and the post-purchase journey should know the difference.

• Customer experience. Delivery, unboxing, how to use the product and when to expect a result. Support tickets and reviews tell you why people don't come back, and most email agencies never read them.

• The offer. A reason to return that isn't another discount: bundles, refills, rewards, membership benefits.

• Customer data. Whether segments run on real purchase behaviour, and whether every tool in the stack sees the same customer.

An agency working only on sends ends up optimising the one lever left to it, which is usually volume. Attributed email revenue rises with send volume whether or not anything improved, so check what the agency is actually looking at before you look at its report.

How were these agencies compared?

• Scope beyond campaigns and flows. Whether the agency works on subscriptions, customer data, the offer, the customer journey or the site, or only on sends.

• What they track. Whether they measure retention itself, such as returning customer revenue, second-order rate, repeat rate by cohort, customer lifetime value, subscription churn and active subscribers, or only channel numbers like opens, clicks and attributed email revenue.

• Model. Done-for-you retainer, consultancy, audit-led, or email bundled with a Shopify build.

• Published proof. Whether the agency puts numbers, with a baseline and a time window, on work a brand can check.

• Platform. Klaviyo only, or several email platforms.

How do the agencies compare at a glance?

What are the best ecommerce email marketing agencies in the UK?

1. Everboost

Known for: CRM and retention for 7 to 8-figure health and wellness DTC brands in the UK and US. Everboost starts with the business rather than the Klaviyo account: who the brand acquires, what it sells them, what happens after the first order and why customers leave. It then runs customer data, email, SMS, direct mail and subscriptions as one retention programme, built to get more customers coming back, buying more often and staying longer.

Location: London, United Kingdom

Brands include: PhycoHealth, Discount Supplements, SolaWave, Womenli, Fat Cow Skincare, Salt Grooming, VEDIC LAB, Mersey Raw

Key services

• Customer data and analysis. Segmentation on real purchase behaviour, repeat rate by cohort, and predictive work on who is likely to reorder, lapse or cancel, so each message and offer reaches the right customer at the right time.

• Email and SMS. Monthly campaign calendars and full flow libraries (welcome, post-purchase, replenishment, winback, subscription lifecycle), written from the customer's own language and designed in the brand's visual world.

• Subscriptions. Offer and frequency design, product-page subscription widgets, cancellation flows with skip, pause and swap before cancel, and failed-payment recovery.

• The offer and the customer experience. Reasons to come back beyond a discount, and the post-purchase journey built around how customers actually use and reorder the product.

• Direct mail and deliverability. Reaching lapsed buyers email no longer reaches, and fixing inbox placement before sending more.

• The diagnostic. An audit of the business and the account before anything is built, ending in a plan ranked by how much repeat revenue each change can move.

Published results: getting the second order

• Salt Grooming: returning customer sales up 58% in 12 months, and the 30-day repeat purchase rate up 24%.

• VEDIC LAB: 90-day second-order rate up 19%, and revenue from each new customer's later orders up 39% within 180 days of the first.

• Discount Supplements: 60-day repeat rate up 12.2%, with a third less discount per order.

Published results: subscriptions and churn

• PhycoHealth: active subscribers up 42%, twice the share of first orders taken as a subscription, and subscription revenue up 118%.

• Mersey Raw: net subscriber growth of 220% in six months, churn down 13%, and upcoming-order churn down 61.7%.

• Fat Cow Skincare: active subscribers up 32% and MRR up 33%, after both had been falling.

• A UK electrolytes brand: total subscription churn down 17.35% and the failed-payment recovery rate up 81%.

Best for: health and wellness brands with acquisition working that want to get more back from every customer they acquire.

Less suited to: brands looking for the lowest cost per email, or for paid media.

2. Underground Ecom

Known for: A large CRM, retention and email team for DTC brands, named Klaviyo Agency Partner of the Year EMEA 2025.

Location: London, with a team of 120+ working across 25 languages

Key services: Underground Ecom runs CRM audits and roadmaps, CRM strategy, creative, flows, SMS and WhatsApp, plus advanced retention work such as cohort and predictive analysis. Its clients include AG1, Surreal and Osprey, and its MedTerra case study reports a 37% customer retention rate across 2022 with 49% of total revenue from email.

Best for: brands selling across many markets and languages that want a large team and a wide CRM remit.

3. PAASE

Known for: Customer data and retention for ecommerce brands. Its own site says it is "not an email agency", and it focuses on profitable actions rather than ESP-attributed revenue.

Location: United Kingdom

Key services: PAASE joins disparate data sources into a single customer view, reviews which parts of the tech stack and apps actually drive sales, maps the customer journey, and builds email and SMS automation on Klaviyo and Mapp using zero-party data from quizzes, preference centres and forms. Its clients include Elizabeth Arden, Curlsmith, Biomel and Wattbike, and its PÄRLA case study reports a 1,500% revenue increase from marketing automation.

Best for: brands whose customer data and tools don't join up, where the fix starts before the email.

4. Enchant

Known for: eCRM and lifecycle work across several platforms, not only Klaviyo, and Klaviyo's 2026 EMEA UK&I Partner of the Year.

Location: London (Great Portland Street), with offices in Cambridge, Berlin and New York

Key services: Enchant works across Klaviyo, Braze, HubSpot, Iterable and Salesforce, covering audits, flows, list growth, design and HTML builds, copy, deliverability, SMS, push, WhatsApp and loyalty, plus eye-tracking research. It sells projects and subscription packages priced on a 12-month agreement. Its clients include Neal's Yard Remedies, Mubi and Timex.

Best for: brands on Braze, HubSpot or Salesforce, or with a mix of DTC and other customer types.

5. Charle

Known for: Shopify and Shopify Plus builds, with a dedicated email and SMS service, Charle Retain.

Location: London, with phone lines in Manchester and New York

Key services: Charle Retain covers Klaviyo setup, flows, segmentation, design, SMS, deliverability, reporting, audits and migrations, alongside Charle's Shopify development, CRO and SEO work, so the site experience and the email programme sit with one team. It is a Klaviyo Silver Partner, and its Shopify clients include Cambridge Satchel, Candy Kittens and 111Skin.

Best for: Shopify brands that want the store build and email handled together.

6. Get Better

Known for: Klaviyo management for ecommerce brands, starting with a paid audit.

Location: Barnstaple, North Devon

Key services: Get Better runs Klaviyo setup and management, flow optimisation, content plans, copy, design, A/B testing and reporting, and describes itself as one of two UK Klaviyo Elite partner agencies. It publishes audit prices from £199 + VAT. Its clients include PerfectTed, MOMA Foods and Studio10 Beauty, and its PerfectTed case study reports flow revenue up 245.63%.

Best for: brands that need Klaviyo itself run well, with subscriptions and the wider customer journey handled elsewhere.

How much does an ecommerce email marketing agency cost in the UK?

Most charge a monthly retainer scoped after an audit, and few publish a figure. Some publish parts of their pricing: Get Better lists audits at £199, £399 and £800 + VAT, and Enchant publishes subscription tiers priced on a 12-month agreement.

Klaviyo, SMS credits and your subscription app bill you separately for their own software. So compare quotes on scope: how many campaigns, which flows, and whether subscriptions, the offer, customer data and direct mail are in it at all.

What should you ask an email agency before signing?

• How do you define retention, and what does it cover beyond email? A good answer includes the subscription, the offer, the customer experience and what acquisition brings in.

• What do you track to know your work is having an impact? Ask which retention numbers they report every month, such as returning customer revenue, second-order rate, repeat rate by cohort and subscription churn, and how they separate their effect from customers who would have bought anyway.

• How do you justify your fee? Ask what return they expect, measured on which numbers, and over what time frame.

• Is our subscription programme in scope? Ask who owns the subscription offer, the cancel flow and failed-payment recovery.

• Have you read our reviews and support tickets? That is where the reasons customers don't come back are written down.

• What do you need to know about our acquisition? A good agency asks which channels and offers bring customers in, because that changes what should happen after the first order.

• What will you do about deliverability before sending more? More volume into a weak sender reputation makes things worse.

Where do influencer marketing and email meet?

Acquisition is the clearest example of why an email agency needs to see beyond its own channel. A creator earns the first order. Whether there is a second depends on what happens next: the product experience, the offer, the post-purchase journey and the subscription.

A customer who arrived on a creator's recommendation came for the product, not the price, so the post-purchase sequence should continue that story: how to use the product, when to expect a result, and what the creator's audience said about it. Content from real people using the product keeps working long after the campaign ends, in post-purchase emails, replenishment reminders and winback sends. For how brands generate that content in the first place, see Augmentum's guide to influencer seeding, and for how seeding fits with affiliate, paid influencer and whitelisting, the guide to building an influencer engine.

Deep creator discount codes are the case to plan around. They bring in first orders at a lower margin, and those customers need a stronger reason to come back at full price. Everboost builds that reason into the offer and the post-purchase journey, and judges it on whether the customer orders again.

Frequently asked questions

What is the best ecommerce email marketing agency in the UK?

The one that looks beyond campaigns and flows at what makes customers order again. For CRM and retention run as one programme for health and wellness brands, Everboost. For a large, multi-language CRM team, Underground Ecom. For customer data and tech-stack work, PAASE. For several email platforms, Enchant. For a Shopify build and email together, Charle. For audit-first Klaviyo management, Get Better.

What should an email agency look at beyond campaigns and flows?

Subscriptions (churn, the cancel flow and failed payments), acquisition (which channels and offers bring customers in), the customer experience after the first order, the offer, and customer data. Those decide whether a customer comes back, and an agency that only sees the email calendar can only work on the messages.

What does an ecommerce email marketing agency do?

It plans, writes, designs and sends a brand's email and usually SMS: the monthly campaign calendar, automated flows such as welcome, abandoned basket, post-purchase and winback, segmentation and deliverability. The better ones also work on the subscription, the offer and customer data.

What is the difference between an email agency and a retention agency?

An email agency works on the channel: campaigns, flows and the numbers they produce. A retention agency works on whether customers come back, which means the subscription, the offer, the customer experience and acquisition as well, with email and SMS as two of the ways it reaches them.

Is email marketing still worth it in 2026?

Yes for ecommerce, because it reaches customers who have already bought at almost no cost per message, so a second order costs very little to win. It works best on a clean list with fixed deliverability, segmented by purchase behaviour rather than sent to everyone.

How long before an email agency shows results?

Fixes to flows and deliverability usually show in the first month or two. Changes to second-order rate, repeat revenue and subscription churn take a quarter or more, because a full purchase cycle has to pass before you can measure them.

Do email agencies run subscriptions too?

Some do. Ask directly, because many stop at the subscription emails and never touch the offer, the cancel flow or failed-payment recovery, which is where most subscription revenue is kept or lost.

How should an email agency handle customers from influencer campaigns?

As their own group. Customers who arrived through a creator or a creator's discount code should get a post-purchase sequence that continues what the creator said about the product, a reminder timed to when it runs out, and a reason to reorder at full price.

Acquisition is the half we run. If you want the creator side looked at alongside your email and retention programme, let's talk. Augmentum Media builds influencer engines for health and wellness DTC brands, from seeding and affiliate to paid influencer and whitelisting.