Picking an email platform for an agency is annoying for one reason: most tools look great in a demo.
Nice dashboards. Clean automations. AI this, personalization that.
Then real agency life starts.
A client wants separate billing. Another one needs approval flows. A third has a messy Shopify setup, bad list hygiene, and expects “better deliverability” by next Tuesday. Your team needs to move fast without breaking reporting, permissions, or automations that someone built six months ago and forgot to document.
That’s where the shiny feature lists stop helping.
The reality is, the best email marketing tool for agencies in 2026 is not the one with the most features. It’s the one your team can actually run across multiple clients without wasting hours on workarounds, account sprawl, or support tickets.
I’ve used most of the major options in agency settings—retainer clients, ecommerce brands, B2B lead gen, small teams, bigger teams, messy handoffs, all of it. Some tools are powerful but painful. Some are easy but hit a ceiling fast. A couple are genuinely good for agencies, but for different reasons.
So if you’re wondering which should you choose, here’s the practical version.
Quick answer
If you want the short version:
- Best overall email marketing tool for agencies in 2026: HighLevel
- Best for ecommerce agencies: Klaviyo
- Best for advanced automation in SMB/B2B: ActiveCampaign
- Best for simple newsletter-focused clients: Mailchimp
- Best budget option for smaller agencies: Brevo
If I had to choose one tool for most agencies, I’d pick HighLevel.
If I ran a pure ecommerce retention agency, I’d pick Klaviyo.
That’s really the fork in the road.
What actually matters
A lot of reviews compare templates, AI subject lines, drag-and-drop builders, and how many integrations a tool has.
That stuff matters a little. But for agencies, the key differences are usually somewhere else.
1. Multi-client management
This is the big one.
Can your team manage multiple client accounts cleanly?
Not “technically possible.” Actually manageable.
You want:
- separate workspaces or sub-accounts
- easy switching between clients
- role-based permissions
- reusable assets
- clean reporting by account
- minimal log-in chaos
A tool can be brilliant for one business and still be terrible for an agency.
2. Speed of execution
In practice, the best platform is often the one that lets your team launch faster.
Can a strategist set up a flow without needing a dev every time?
Can you clone automations across accounts?
Can junior team members safely work inside client setups?
If every new client setup feels like rebuilding the wheel, your margins disappear.
3. Reporting clients actually care about
Clients do not care that your platform has “advanced analytics.”
They care about:
- revenue from email
- list growth
- deliverability trends
- flow performance
- campaign performance
- leads booked or deals influenced
The reporting needs to be easy to explain in a monthly call.
4. Billing and account structure
This gets ignored until it becomes a problem.
Some agencies want one master account with sub-accounts. Others want each client to own billing directly. Some need white-label logins. Some need to hand over the setup later.
If your business model depends on retainers, upsells, or reselling software, this matters a lot.
5. Deliverability control
No tool magically fixes bad deliverability. That’s a myth.
But some make it easier to manage domain setup, warm-up practices, list hygiene, suppression, segmentation, and sending reputation across clients.
Agencies dealing with messy lists need tools that don’t hide the important stuff.
6. Depth vs usability
This is where most trade-offs live.
A more powerful tool often means:
- more setup time
- more room to break things
- more training needed
A simpler tool often means:
- faster onboarding
- easier handoff
- less flexibility later
You’re not choosing the “best platform.” You’re choosing the best friction level for your agency.
Comparison table
Here’s the simple version.
| Tool | Best for | Main strength | Main weakness | Agency fit |
|---|---|---|---|---|
| HighLevel | Full-service agencies | Multi-client setup, white-labeling, CRM + email + SMS in one place | Email builder/reporting not as polished as ecommerce-first tools | Excellent |
| Klaviyo | Ecommerce agencies | Best ecommerce segmentation, flow logic, revenue attribution | Less agency-native for non-ecommerce clients | Excellent for ecommerce |
| ActiveCampaign | B2B/SMB automation | Powerful automations and flexible journeys | Multi-client management is clunkier than agency-first tools | Good |
| Mailchimp | Small/simple clients | Easy to use, familiar, fast to launch | Gets expensive and limiting as complexity grows | Fair |
| Brevo | Budget-conscious agencies | Good value, email + SMS, simple setup | Less depth, weaker ecosystem and advanced reporting | Good for basic needs |
| HubSpot | Larger B2B clients | CRM alignment, strong sales/marketing reporting | Expensive, heavy, overkill for many agency accounts | Strong but costly |
| MailerLite | Very small clients | Clean UI, low cost, easy campaigns | Not built for agency-scale complexity | Limited |
- HighLevel for broad agency operations
- Klaviyo for ecommerce retention
- ActiveCampaign for automation-heavy B2B
- Mailchimp or Brevo for simpler, lower-budget clients
Detailed comparison
1) HighLevel
HighLevel has become the default agency answer for a reason.
It was built around the agency model, not retrofitted into it later.
The sub-account structure is the main advantage. If you manage multiple clients, this immediately makes sense. You can create client accounts, manage permissions, clone assets, standardize setups, and even white-label the experience. For agencies selling marketing systems, not just email campaigns, that’s a big deal.
It also combines a lot of tools agencies usually stitch together:
- email marketing
- SMS
- forms
- landing pages
- CRM
- pipeline tracking
- automations
- calendars
- reputation management
That matters because many agencies in 2026 are not just “email agencies.” They’re doing lifecycle marketing, lead nurture, appointment booking, sales follow-up, and client reporting in one package.
Where HighLevel wins:
- managing many clients in one ecosystem
- white-labeling
- service delivery plus software resale
- agencies that want recurring software revenue
- local lead gen and service business clients
Where it’s weaker:
- email design is decent, not best-in-class
- reporting is useful, but not as clean as Klaviyo for ecommerce revenue
- some parts still feel like “all-in-one software” instead of specialist software
- if your team only does high-end email strategy, it can feel broad rather than deep
Contrarian point: some agencies adopt HighLevel too early.
If you only have five small clients and mostly send newsletters, HighLevel can be more system than you need. You may spend more time setting up infrastructure than improving campaigns.
Still, for a real agency operation, it’s hard to beat on practicality.
2) Klaviyo
For ecommerce, Klaviyo is still the one to beat.
I’ve seen agencies try to force generalist platforms into Shopify retention work, and it usually ends the same way: awkward segmentation, weaker attribution, and more custom work than necessary.
Klaviyo is best for:
- Shopify and Shopify Plus brands
- retention agencies
- DTC brands
- clients who care about flows, AOV, repeat purchases, and product-based segmentation
Its strength is not just automation. It’s ecommerce context.
You can build campaigns around:
- viewed product
- added to cart
- started checkout
- purchased specific categories
- predicted churn
- repeat buyer windows
- product affinity
- customer lifetime value behavior
That sounds obvious now, but the difference in daily use is huge. Your team can move from idea to launch fast because the data model already fits ecommerce.
Where Klaviyo wins:
- ecommerce segmentation
- revenue attribution clients understand
- strong flow performance
- product feed and catalog logic
- integrations with ecommerce stack tools
Where it’s weaker:
- not ideal for mixed agency rosters with local businesses, B2B, and service brands
- less compelling if email is only one small part of your service
- can get expensive as lists grow
- account management is fine, but not agency-native in the same way as HighLevel
Another contrarian point: Klaviyo is sometimes overkill for low-volume stores.
If a client has a tiny list, weak traffic, and barely any purchase history, they may not need sophisticated predictive segmentation. They may need better offers, better popups, and consistent campaigns. A cheaper tool can be enough for a while.
But if you’re serious about ecommerce retention, Klaviyo is still best for most agencies in that niche.
3) ActiveCampaign
ActiveCampaign sits in an interesting middle ground.
It’s more powerful than simple newsletter tools, more automation-friendly than Mailchimp, and often more approachable than enterprise systems. For B2B and SMB lifecycle work, it’s still a strong option.
What I’ve always liked about ActiveCampaign is the automation builder. It’s flexible without feeling completely out of control. You can create nuanced journeys based on behavior, tags, lead scoring, CRM stages, and event-based triggers.
That makes it good for:
- lead nurture
- webinar funnels
- onboarding sequences
- sales follow-up
- SaaS lifecycle campaigns
- hybrid email + CRM workflows
Where it wins:
- automation depth
- CRM-connected journeys
- lead scoring
- decent balance of power and usability
- strong fit for B2B agencies
Where it loses:
- managing many separate client accounts is not as smooth as HighLevel
- handoffs can get messy if automation logic grows fast
- pricing can creep up
- reporting is solid, but not always client-friendly out of the box
If your agency has a few higher-value B2B clients and does serious nurture work, ActiveCampaign can be excellent.
If you have 30 clients and need operational efficiency across all of them, it starts to feel less ideal.
4) Mailchimp
Mailchimp is still around because it still solves a real problem: getting basic email done with minimal friction.
That matters more than people like to admit.
For small clients, founder-led brands, local businesses, nonprofits, and teams that just need regular campaigns, Mailchimp is often enough. The interface is familiar. Training people is easy. Handoffs are easier than with more complex systems.
Where Mailchimp works:
- newsletter programs
- basic automations
- simple audience management
- clients who may take over later
- low-complexity campaign calendars
Where it falls short:
- advanced segmentation is limited compared to Klaviyo or ActiveCampaign
- agency management isn’t its core strength
- pricing becomes less attractive over time
- serious automation work can feel restrictive
The biggest mistake agencies make with Mailchimp is either dismissing it entirely or relying on it too long.
It’s not sexy, but it’s good for certain clients.
It’s also not a smart long-term home for clients whose needs are clearly growing into lifecycle or ecommerce retention complexity.
5) Brevo
Brevo keeps getting better, and a lot of agencies still underrate it.
It’s not the most exciting platform, but it offers solid value. For smaller agencies or clients with modest budgets, it can cover a surprising amount without the pricing pain of larger tools.
It’s especially decent if you want:
- email plus SMS
- transactional messaging options
- simple automations
- straightforward contact management
- lower cost at moderate scale
Where Brevo wins:
- price-to-value
- simplicity
- decent breadth for smaller teams
- practical for agencies with budget-sensitive clients
Where it loses:
- less depth in advanced segmentation and strategy-heavy work
- weaker “wow” factor in reporting and ecosystem
- not the first pick for high-growth ecommerce or sophisticated B2B funnels
I wouldn’t call Brevo the best email marketing tool for agencies overall.
But for lean teams managing practical client programs, it’s a sensible option.
6) HubSpot
HubSpot is a bit of a different category.
For some agencies, especially B2B-focused ones serving larger clients, it’s incredibly strong. If the client already lives in HubSpot Sales Hub and uses the CRM seriously, the email side becomes much more useful because it sits inside a broader revenue system.
That means:
- marketing and sales alignment
- lifecycle stage tracking
- cleaner attribution across pipeline
- better visibility into influenced revenue
Where HubSpot wins:
- B2B reporting
- CRM integration
- enterprise-ish structure
- sales and marketing alignment
Where it hurts:
- cost
- complexity
- slower setup
- overkill for many SMB clients
- not ideal if your agency wants lightweight deployment across many accounts
HubSpot is often best for fewer, larger clients—not a high-volume agency roster.
7) MailerLite
MailerLite deserves a mention because some agencies genuinely do not need more.
It’s clean, easy, inexpensive, and good for basic campaign execution. For creators, small brands, and simple email programs, it’s pleasant to use.
But from an agency perspective, it hits limits quickly. You can make it work, sure. But if your clients expect more than newsletters and basic automations, you’ll outgrow it.
Real example
Let’s make this practical.
Say you run a 9-person agency in 2026.
Your client mix looks like this:
- 6 local service businesses
- 4 B2B SaaS clients
- 5 Shopify brands
- 3 small founder-led brands with simple newsletters
Your team has:
- 1 strategist
- 2 email specialists
- 1 automation person
- 1 designer
- 2 account managers
- 1 ops lead
- 1 part-time developer
Which should you choose?
If you try to force every client into one tool, you’ll probably create unnecessary pain.
Here’s what usually works better:
Option A: HighLevel as the agency standard, with Klaviyo for ecommerce
This is the setup I’d probably use.
- HighLevel for local service businesses and maybe some B2B nurture work
- Klaviyo for Shopify brands
- MailerLite or Mailchimp only for tiny newsletter-only accounts if needed
Why this works:
- local/service clients benefit from CRM, forms, booking, SMS, and pipelines
- ecommerce clients get the revenue and segmentation depth they need
- your team isn’t forcing ecommerce retention into an all-in-one tool that’s merely “good enough”
The downside:
- your team learns two core systems instead of one
- internal documentation matters more
- reporting across the agency is less standardized
Still, this is often the most realistic setup.
Option B: HighLevel for almost everything
Some agencies do this to simplify operations.
It can work if:
- your ecommerce clients are not highly sophisticated
- your team values one system over best-in-class specialization
- your margins depend on speed and standardization
The downside is obvious: your best ecommerce clients may eventually want more than HighLevel is strongest at.
Option C: ActiveCampaign + Klaviyo
This is a strong combo for agencies focused on B2B automation and ecommerce retention.
It works well when:
- you don’t need white-label software resale
- you have fewer clients, but deeper strategic work
- your team is comfortable with more specialized systems
The downside:
- multi-account agency operations are less elegant
- more admin overhead
- less unified client experience
That’s the real trade-off agencies face. Not “which tool has the best drag-and-drop editor,” but how much operational complexity you’re willing to absorb.
Common mistakes
Agencies get this decision wrong in pretty predictable ways.
1. Choosing based on feature count
More features does not mean better for your team.
A bloated tool can slow execution, confuse junior staff, and create fragile setups nobody wants to touch.
2. Ignoring client mix
This is probably the biggest mistake.
If 70% of your revenue comes from ecommerce, choose like an ecommerce agency.
If most clients are local businesses and service brands, choose like that.
Don’t buy based on aspirational positioning.
3. Underestimating account management pain
Switching between clients, setting permissions, handling approvals, cloning assets—this stuff either saves time every week or quietly burns it.
Agency operations are where many tools fall apart.
4. Assuming deliverability is tool-dependent
A platform helps, yes.
But poor list quality, bad sending habits, weak segmentation, and neglected domain setup matter more. I’ve seen agencies blame the tool when the real issue was sending campaigns to cold, bloated lists every week.
5. Standardizing too aggressively
This is a bit contrarian, but not every client needs to live in your “main stack.”
Sometimes the right move is to keep a small client on a simpler platform instead of migrating them into your preferred system just for internal consistency.
6. Forgetting handoff reality
If a client may bring email in-house later, choose a platform their internal team can realistically use.
A highly customized setup might impress them now and annoy them later.
Who should choose what
Here’s the direct version.
Choose HighLevel if:
- you run a full-service agency
- you manage lots of client accounts
- you want white-labeling
- you sell software access or recurring systems
- many clients are local businesses, coaches, service brands, or lead gen focused
Choose Klaviyo if:
- you are an ecommerce agency
- most clients are on Shopify
- retention marketing is a core service
- clients care about revenue attribution, flows, segments, and product behavior
- you want best for ecommerce, not best for everything
Choose ActiveCampaign if:
- you focus on B2B or lifecycle automation
- your clients have longer sales cycles
- lead scoring and CRM workflows matter
- you have fewer accounts but deeper strategic work
Choose Mailchimp if:
- your clients are simple
- newsletters are the core deliverable
- clients may manage things themselves
- you want easy onboarding and less training overhead
Choose Brevo if:
- budget matters a lot
- clients need email and SMS without premium pricing
- your programs are straightforward
- you want practical value over advanced complexity
Choose HubSpot if:
- your clients are larger B2B companies
- sales and marketing alignment is central
- CRM-driven reporting matters more than low cost
- you can justify the price
Choose MailerLite if:
- clients are very small
- campaigns are simple
- budget is tight
- you don’t need much beyond the basics
Final opinion
If you want one answer, here it is:
HighLevel is the best email marketing tool for agencies in 2026 overall.Not because it’s the prettiest. Not because it has the deepest email feature set. Not because every client should use it.
It wins because agency life is messy, and HighLevel is built for that mess.
It handles multi-client structure better than most alternatives. It gives agencies more control over delivery, permissions, systems, and recurring service models. If your business is about managing accounts at scale, standardizing operations, and keeping work inside one ecosystem, it’s the most practical choice.
But—and this matters—Klaviyo is the better tool for ecommerce agencies.
If your agency’s reputation depends on increasing retention revenue for Shopify brands, I would not choose HighLevel as my main ecommerce platform. I’d choose Klaviyo and not overthink it.
So which should you choose?
- Most agencies: HighLevel
- Ecommerce agencies: Klaviyo
- B2B automation shops: ActiveCampaign or HubSpot, depending on budget and complexity
- Small/simple client work: Mailchimp or Brevo
That’s the honest version.
FAQ
What is the best email marketing tool for agencies with multiple clients?
For most agencies, HighLevel is the best fit because of sub-accounts, white-labeling, and all-in-one client management. If your clients are mostly ecommerce brands, Klaviyo is usually the better specialized option.
Which tool is best for ecommerce agencies in 2026?
Klaviyo is still best for ecommerce agencies, especially those working with Shopify brands. Its segmentation, flow logic, and revenue attribution are still ahead of more general tools.Is Mailchimp still worth using for agencies?
Yes, for certain clients. It’s still useful for small businesses, newsletter-heavy accounts, and simple handoff situations. It’s just not the best choice once automation, segmentation, or multi-client complexity increases.
What are the key differences between HighLevel and ActiveCampaign?
HighLevel is more agency-first, with better multi-client management and white-labeling. ActiveCampaign is stronger for nuanced automations and B2B lifecycle journeys. If you’re asking which should you choose, it usually comes down to operational scale vs automation depth.
Should an agency use one email platform for every client?
Usually not. In practice, a two-platform setup often makes more sense—something like HighLevel + Klaviyo or ActiveCampaign + Klaviyo. Forcing every client into one tool can create more problems than it solves.