Best Email & SMS Retention Agencies For DTC Brands In 2026

Pick the agency that matches your revenue band and your email-to-SMS split, not the one with the longest client list. For a DTC brand above roughly $10M, a Klaviyo specialist with named clients in your vertical is the safer hire. Below that, a published entry price and a short contract matter more.

This applies when your flows already run on Klaviyo and email plus SMS bring in under about 30% of store revenue. Above that share, you need an optimisation partner rather than a rebuild.

Every results figure in this list is reported by the agency itself. Use the list to build a shortlist you then audit, because it is not a ranking of proven outcomes.

Email & SMS Retention Agencies At A Glance

Four agencies are profiled below, and every figure in this table is reported by the agency itself and has not been audited. The numbers show list order, not a scored ranking.

1. InboxArmy: Best For Brands Wanting A Stated Entry Price

InboxArmy states it has partnered with 5000+ brands since 2016, and it sells managed services and shows both email and SMS revenue totals. It is also the only agency in this list that puts a monthly figure on the page, a $1,500 minimum for managed services.

InboxArmy's homepage shows $1B+ labelled Email Revenue Generated and $115M+ labelled SMS Revenue Generated, and the page does not say how either was measured. Read them as scale signals. They are not evidence of what the agency would do for your account. InboxArmy also states a 90% client retention rate and 4.9/5 from 100+ verified reviews, which are easy to ask about on a reference call.

Who it is for: Brands that want to know the entry price before they book a call. Under the fit rule later in this guide, that usually means brands below about $10M, though InboxArmy states no client-size band of its own. InboxArmy's FAQ says brands it works with have seen anywhere from a 10% to 400% lift. A range that wide forecasts nothing, so ask for the median and the baseline. The homepage also lists a Maven Lane case study with $700K+ revenue in 6 months and a Patriot Gold testimonial citing a 140% increase in revenue. Ask for the dates and starting points behind both.

Pricing: InboxArmy's FAQ states a $1,500 per month minimum for managed services and says final pricing depends on needs and budget. It also mentions a Dedicated Resource contract and gives no price for it.

Strengths:

• A stated entry price lets you screen cost before a first call.
• A start year and a brand count give you a track record to check on references.
• A published retention rate and review score are claims you can ask the agency to source.
• Two named case examples give you something specific to ask about.

Trade-offs:

• The revenue totals come with no stated measurement method.
• The lift range is too wide to use as a forecast.
• No client-size band or vertical focus is stated, so you cannot tell whether brands like yours are typical clients.
• The Dedicated Resource contract has no price, so the stated minimum is a floor and not a quote.

Key capabilities:

• Managed email services.
• Managed SMS services.
• A Dedicated Resource contract, mentioned in the FAQ with no price or inclusions stated.
• Published case examples and testimonials.

Good fit:

• Brands that want a price floor before a first call.
• Brands that want to compare a stated minimum against agencies that quote only on request.
• Brands that will check the review claims themselves before signing.

Not a fit:

• Brands that need a firm all-in quote, since final pricing depends on needs and budget.
• Brands that want results with a stated measurement method.
• Brands that need an agency with a stated vertical focus.

The limitation that matters most is that none of InboxArmy's headline revenue figures say how they were measured.

2. Flowium: Best For Brands Wanting A Price Lock

Flowium's homepage states it has worked with 1000+ brands since 2017, and it lists Transparent Pricing and a 2 Years Price Lock Guarantee as features. Transparent Pricing is a feature on the page, yet the page carries no price figures.

Flowium also lists separate Klaviyo Agency and Klaviyo Experts service pages, so its work centres on Klaviyo. The homepage claims no Klaviyo partner tier. That is not a mark against it, but it means you should ask what credential backs the Klaviyo focus.

Who it is for: Brands that want to test the relationship before paying for it. Flowium offers a free, no-commitment lifecycle diagnosis and a 30-minute call, which lets you judge the thinking before you sign anything. Under the fit rule later in this guide, that makes it a natural first call for brands below about $10M, though Flowium states no client-size band.

Pricing: Flowium's homepage states no figures, so the table reads Pricing on request. The only price-related terms it gives are the price lock and the free diagnosis.

Strengths:

• A stated brand count and start year give you a track record to check on references.
• A price lock is a contract term you can ask to see in writing.
• A free diagnosis lets you judge the thinking before you commit.
• Dedicated Klaviyo service pages show where the agency's work centres.

Trade-offs:

• Transparent Pricing is claimed but no figures appear, so you cannot compare its cost with the other agencies.
• No Klaviyo partner tier is named on the homepage, so confirm status in Klaviyo's directory yourself.
• The homepage states no client-size band or vertical focus, so fit is unclear until the first call.

Key capabilities:

• Klaviyo agency services.
• Klaviyo expert support.
• A free lifecycle diagnosis with a call.
• A price lock guarantee on its terms.

Good fit:

• Brands that want a free diagnosis before any contract.
• Brands whose main worry is price creep after the first year.
• Brands already on Klaviyo that want an agency with service pages dedicated to it.

Not a fit:

• Brands that need price figures to compare before a call.
• Brands that require an agency-stated Klaviyo partner tier.
• Brands that want published results to audit before a first conversation.

The limitation that matters most is that the homepage gives no price figures, so there is nothing to compare until you take the call.

3. Retain Marketing Agency: Best For Comparing Published Case Studies

Klaviyo's partner directory lists Retain Marketing Agency as a Klaviyo Partner with no tier shown. The listing's headline claim is that the agency adds 35% to brands' revenue.

The same listing cites 396% growth in automated email flows for a US sneaker brand and 642% revenue growth from email for a German bed-linen brand. Both are self-reported and undated, so neither tells you how long the growth took or what the starting point was. A percentage on a small base can look dramatic, which is why the baseline matters more than the headline.

Who it is for: Brands that want to read specific case claims before talking to anyone, in a directory Klaviyo hosts. The two cases span two verticals and two countries, so you can see quickly whether either looks like your own business. This guide draws on one source for the agency, the Klaviyo listing, so the profile is thinner than the others.

Pricing: The Klaviyo listing shows no price, so the table reads Pricing on request.

Strengths:

• Klaviyo's directory is a place where you can check the partner status yourself.
• The listing gives two specific case claims with a named channel and a market, so you can ask for the detail behind each.
• The cases cover two different verticals, which helps you judge how widely the work applies.

Trade-offs:

• No partner tier is shown in the listing.
• Both case claims are self-reported and undated.
• Growth percentages with no stated baseline say little about the size of the result.
• The listing gives no price and no client-size band.

Key capabilities:

• Klaviyo-focused work, as a listed Klaviyo Partner.
• Automated email flows, per the sneaker brand case.
• Email revenue growth, per the bed-linen brand case.

Good fit:

• Brands that want to compare published case claims across agencies.
• Brands that sell physical products and want to see whether a case resembles their own.
• Brands that will ask for the underlying numbers before shortlisting.

Not a fit:

• Brands that require a stated partner tier.
• Brands that need a published price.
• Brands that want a full services list before a first call.

The limitation that matters most is that both cases are undated and self-reported, with no tier shown to help you weigh them.

4. Sticky Digital: Best For $10M+ Beauty, Wellness, And Subscription Brands

Sticky Digital states that it is a Klaviyo Platinum Partner, active since 2019, offering Klaviyo email, SMS and migrations to Klaviyo. It states it serves DTC brands doing $10M and up in beauty, wellness and supplements, baby and kids, consumables, and subscription.

Sticky Digital's stated clients include Murad, U Beauty, ZO Skin, Paula's Choice and IM8 Health. Sticky Digital reports that clients usually see 25% to 40% of store revenue coming from email within six months.

Who it is for: DTC brands doing $10M and up in the verticals Sticky Digital names. If your brand sits in one of those verticals and above that revenue band, this is the profile in the list that states a band matching yours.

Pricing: Pricing on request.

Strengths:

• States a Klaviyo partner credential and a start year, both of which you can ask the agency to document.
• States a client-size band and five verticals, which makes the fit question easy to answer.
• Names five clients you can ask about.
• Covers migrations to Klaviyo as well as email and SMS.
• Gives a revenue-share outcome with a stated timeframe.

Key capabilities:

• Klaviyo email programmes.
• SMS programmes.
• Migrations to Klaviyo.
• Work across beauty, wellness and supplements, baby and kids, consumables, and subscription brands.

Good fit:

• DTC brands in the revenue band Sticky Digital states.
• Brands in the verticals Sticky Digital names.
• Brands moving to Klaviyo that want migration and ongoing email and SMS from one team.

Not a fit:

• Brands below the revenue band Sticky Digital states.
• Brands outside the verticals Sticky Digital names.
• Brands that need a published price before a first conversation.

The limitation that matters most is that pricing is on request, so cost is only known after a conversation.

What An Email And SMS Retention Agency Actually Does

Most agencies sell sends. The good ones sell flows. The difference decides whether the fee pays for itself.

An email agency handles sends and creative. A retention agency plans the lifecycle across email, SMS and loyalty. If you buy the first and expect the second, you will pay for a campaign calendar and wonder why nothing compounds.

Flows are where the fee is earned. Klaviyo's benchmark data from over 183,000 customers shows flows are 5.3% of email sends but produce nearly 41% of email revenue. The same benchmark puts a good click rate at 1.69% for campaigns and 5.58% for flows. Per send, a flow does far more work than a campaign, so an agency that only manages the campaign calendar is ignoring the highest-yield part of the programme.

The platform underneath matters too. If you are still choosing one, start with the best email marketing tool for Shopify or compare email marketing platforms by list size. Pick the platform first, because an agency that works inside the wrong tool spends its first months on workarounds.

How These Agencies Were Chosen

Four agencies are profiled, and one rule decides what appears in each profile. A claim is included only if the agency states it on its own site or in its Klaviyo directory listing, and every such claim is attributed to the agency. No figure has been independently audited. Sticky Digital's profile uses details the agency supplied, and they are attributed to it in the same way.

Each profile covers these eight attributes:

• What the agency does.
• Who it is for.
• Pricing.
• Strengths.
• Trade-offs.
• Key capabilities.
• Good fit.
• Not a fit.

Where an agency's own facts do not support an attribute, the profile leaves it out rather than guess. Where an agency publishes no price, the profile says Pricing on request. The numbers in the headings show list order and are not a scored ranking.

Other agencies exist that are not profiled here, because their own pages could not be read during research. A shorter list built on readable facts is more useful to you than a longer one padded with third-party descriptions.

Email Versus SMS: How To Split The Work

Email carries flows and campaigns. SMS carries messages where timing matters, and it needs its own cost and consent discipline. The agency you hire should be able to explain how it splits the work between the two before you sign.

Hire one team for email and SMS when both channels send to the same customers out of the same Klaviyo account, because one team can see both schedules and stop a customer receiving two conflicting messages in the same hour.

An SMS-only specialist makes sense when your email is already run well in-house and you want one added channel. The cost is coordination. Two agencies each optimise their own channel's numbers, and nobody owns the customer's whole week.

Attribution adds a second reason to keep the work together. Klaviyo's Help Center sets default attribution windows for new accounts, with email clicks and opens counted for 5 days, SMS clicks for 5 days and SMS deliveries for 12 hours. Because the windows differ by channel, ask how the agency's report assigns credit when a customer saw both an email and a text before ordering.

Do not accept a vague answer on consent. This guide does not cover SMS legal requirements, so ask each agency how it handles consent and get the answer in writing.

Flows run on automation software, and email automation tools for scalability covers the options if yours is holding the programme back.

How To Choose Between Them: A Fit Rule By Revenue Band And Email-To-SMS Split

You can apply this rule in five minutes, with numbers you already have.

1. Measure the share of store revenue that email and SMS bring in. Under about 30% is a structural gap rather than a performance dip. Flows unchanged for six months, or paid spend above $20,000 a month, are the other signs an agency is due.
2. Place your brand in a revenue band. Below $10M, favour a stated entry price, a short contract and a free diagnosis before any commitment. InboxArmy's FAQ states a $1,500 per month minimum, and Flowium offers a free diagnosis and a 30-minute call. At $10M and above, favour named clients in your vertical and a stated partner tier. Sticky Digital states a band of $10M and up.
3. Place your brand on the email-to-SMS split. If SMS is already a meaningful channel, favour one team that runs both. InboxArmy shows an SMS revenue figure and Sticky Digital lists SMS among its services. This guide's sources do not state the SMS scope of Flowium or Retain Marketing Agency, so ask both to confirm it.
4. Compare published case claims last. If case studies matter most to you, Retain Marketing Agency's Klaviyo listing gives two to read, and you can apply the verification steps below to each.

The research verified a client-size band for only one agency. Read this rule as a way to sort the shortlist, and not as a claim about any agency's minimum.

If your list is the bottleneck rather than your flows, fix that before you hire. Email capture tools is the place to start, because a retention programme can only work on the customers you can reach.

How Much Does A Retention Agency Cost?

Most retention agencies publish no price, so the profiles above say Pricing on request. The one published minimum in this list is InboxArmy's $1,500 per month for managed services. Break-even is the monthly retainer plus platform and SMS costs, divided by your margin on the revenue the agency adds.

For a wider reference point, Darkroom Agency's FAQ puts Klaviyo agency retainers at $5,000 to $10,000 a month for brands between $5M and $30M. Darkroom cites no source for that range. Use it as a reference point and not as a rate card.

The number that matters is not the retainer. It is the retainer against what the programme adds. Here is a worked example with round numbers. They are illustrative, not a benchmark.

• Monthly retainer: $6,000
• Extra platform and SMS costs the programme causes: $2,000 a month
• Total monthly cost: $8,000
• Margin on incremental revenue: 40%
• Break-even incremental revenue: $8,000 divided by 0.40, which is $20,000 a month

If the programme adds less than $20,000 a month in revenue you can trace to the agency's work, it loses you money that month. Use your real margin. At a 25% margin, break-even in this example rises to $32,000 a month. Count only the platform and SMS spend that the programme adds, not the subscription you would pay anyway.

If you are weighing a retainer for search as well, the same break-even logic applies to our ongoing search and AI-visibility retainer.

Agency, In-House Hire, Or Fractional Marketer?

If you cannot say who owns flow maintenance after the first 90 days, you need a retained team. A hire who leaves, a freelancer who is busy, or a founder who is distracted all leave flows to go stale.

Choose an agency when you need strategy, builds, SMS and reporting from one team and you cannot yet keep one specialist busy full time.

An in-house hire needs tooling to be effective, and AI marketing tools for ecommerce shows what is available. A fractional hire gives you senior judgement without a full team, but someone still has to do the building.

Once retention is running, the next question is whether AI shopping assistants recommend you at all. Our AI search visibility work covers that, and ecommerce GEO agencies lists other options if you want to compare.

How To Verify An Agency's Self-Reported Results

Every figure in this list is agency-reported. That makes your own checking the real ranking. Work through these six steps before you sign anything.

1. Check the attribution window first. Klaviyo's Help Center sets default windows for new accounts that count email clicks and opens for 5 days, SMS clicks for 5 days and SMS deliveries for 12 hours, so a figure quoted on a longer window is not comparable with a default report. Ask which window was used.
2. Ask for three case studies in your vertical and revenue band. A sneaker brand's growth tells a bed-linen brand very little.
3. Ask for read-only access to the Klaviyo account during the pitch. An agency confident in its work will agree.
4. Ask what the baseline was and what else changed in the same period, such as promotions, paid spend or a relaunch.
5. Check the partner tier by name in Klaviyo's partner directory, and compare it with what the agency says on its own site.
6. Set aside any figure with no timeframe until the agency supplies one. InboxArmy's revenue totals state no measurement method, and the two cases in Retain Marketing Agency's Klaviyo listing carry no dates.

Do the same check on your own numbers before the call. Customer insights tools for email data helps you see which flows and segments already earn, so an agency's claim has something to be measured against.

Questions To Ask Before You Sign

Take these questions into the first call:

• How long is the contract, and what does it cost to cancel?
• Are there setup fees, and what exactly do they cover?
• Will you put a price lock in writing, given Flowium advertises a 2 Years Price Lock Guarantee?
• Who owns the Klaviyo account, the flows and the templates when the contract ends?
• How do you monitor deliverability, and which email deliverability tools do you use?
• How many flows will you build in the first quarter?
• Who is my senior contact, and how often will I speak with them?
• Is there a free diagnosis before I commit to anything?
• Will you give me read-only access to the account before I sign?

As a rule of thumb, expect roughly 12 to 18 flows for a mid-market account in the first quarter. Fewer than that needs an explanation, and more than that needs proof that the extra flows earn something.

Walk away from pitches that skip discovery or withhold account access. An agency that will not look at your account before quoting is selling a package, and an agency that will not let you look at its work is asking for trust it has not earned.