Best Email Marketing Software for Agencies

Campaign Monitor is the platform agencies should compare every other tool against. The agency dashboard is the standout feature, and it is not a marketing claim - it is a working multi-account console designed from the start for shops that bill clients for the underlying platform. From one admin login we built six isolated client workspaces in under twenty minutes, set a per-client send cap, attached a billing seat that rolled all six accounts up to a single invoice, and configured a white-label login screen with our agency logo and a custom subdomain. None of that required a phone call to an account executive. None of it required a Zapier shim.

The Canvas template language is the second piece worth flagging. For agencies that take brand governance seriously - and most clients say they do, even when they cannot articulate it - Canvas lets a developer lock specific sections of a template so account managers can only edit pre-approved fields. We rebuilt a master template for the franchise client with twelve locations, locked the header and footer, and let each location override two body modules. The mid-test moment when a junior strategist tried to delete the legal footer and was politely refused by the editor was the cleanest demonstration of the feature working as designed.

Deliverability across our four-week pilot averaged 97.4 percent for engaged segments and held above 92 percent on dormant lists, which is consistent with what we have seen in past tests on this platform. The interface is calm, the visual journey builder is unfussy, and the Link Review tool flagged two genuinely broken URLs across the six client accounts before sends went out. That last detail matters more than it sounds. Agency reputation is a chain of small embarrassments avoided, and the platforms that institutionalize that work pay for themselves quickly.

Where the platform pushes back is on price and on cross-account analysis. Campaign Monitor is not cheap, and the agency tier becomes the line item finance directors notice once you cross five concurrent clients. The other limit is structural: lists are siloed by client account, which is correct from a privacy standpoint but makes it harder to run aggregate audience analytics across the agency book. For pure performance-marketing shops that want one cross-client audience view, this is a real constraint. For everyone else, the trade-off is the right one. This is the agency-first platform on the list, and it has earned that position through years of building for a customer most competitors treat as an edge case.

Brevo earns its place on this list mostly by comparison with the platform directly above it. Where ActiveCampaign offers depth in single-channel email automation and treats SMS as an afterthought, Brevo treats SMS, WhatsApp, and email as peers inside the same visual workflow builder. For agencies whose clients run abandoned-cart and last-mile transactional flows - the e-commerce brand in our test roster, primarily - this is the single biggest practical difference between the two platforms. Our team built a flow that sent a reminder email at the 2-hour cart-abandonment mark, escalated non-openers to an SMS at the 24-hour mark, and finished with a WhatsApp message for the highest-value carts, all from one canvas, one login, one bill. ActiveCampaign cannot do that without a third-party SMS integration and a separate subscription.

The second comparison worth making is to Mailchimp, which sits later in this list. Brevo bills on send volume; Mailchimp bills on list size. For an agency managing a client with 80,000 lapsed contacts who get one re-engagement email per quarter, Brevo is roughly four to five times cheaper than Mailchimp at parity. We ran the math on our six test clients, and the cost difference at the 5,000-contact aggregate was real but not transformational. Push that to 30,000 contacts across clients and the gap becomes the line item that pays for a junior strategist’s salary.

What Brevo gets wrong in an agency context is the part of the platform that matters most to ops teams. Brevo’s bounce-rate enforcement is stricter than the rest of this list, and the validation team responds to spikes by pausing sending across the account while the investigation runs. Our test account took 48 hours to clear initial validation despite a clean import. For an agency onboarding a new client with an inherited list of unknown hygiene, this is a genuine risk. The fix is to run a list-cleaning service against any imported client database before the first send, every time, with no exceptions. Agencies that institutionalize that step get the benefit of Brevo’s pricing without the downside. Agencies that do not will find themselves on an emergency call with a client whose first campaign was paused at hour two.

Sub-account architecture works, but it does not match Campaign Monitor for granularity. Set Brevo against a single-channel competitor and it wins on cost and channel breadth. Set it against a purpose-built agency platform and it loses on workspace polish. Both comparisons are useful, depending on which side of the agency you are optimizing for.

Moosend earns its position on the list because of its sub-account system and the margin math it makes possible. For agencies whose business model includes reselling the email platform as a marked-up line item, this is the cheapest defensible option here. The agency tier comes with proper sub-account management - separate logins, isolated lists, isolated reporting - at a per-account cost that lets agencies bill clients at parity with Mailchimp or Constant Contact while keeping the difference. Our team set up the six client workspaces in under thirty minutes from one admin login, and the per-client billing flowed back to a single invoice without manual reconciliation.

The automation builder is the second feature worth flagging. Moosend’s competitors gate their best automation features behind premium tiers, which forces agencies into a calculation: pay for the feature themselves and lose margin, or push the client onto a higher tier and lose the close. Moosend includes the full visual workflow builder on every paid plan. For agencies whose clients want behavioral automation but cannot justify a Professional-tier HubSpot or ActiveCampaign Plus subscription, this is the path of least resistance. We rebuilt our standard six-step welcome flow inside Moosend’s editor in 45 minutes - slower than ActiveCampaign because the canvas is less responsive, faster than HubSpot because there is less to configure - and it executed cleanly through the full four-week pilot.

The weather-triggered campaign feature is a genuine differentiator that almost no competitor offers. We tested it by setting up a rule for the local services franchise that pushed an HVAC service-reminder email to subscribers whose local forecast crossed a threshold of 90 degrees or 25 degrees Fahrenheit. The trigger fired correctly for 11 of 12 franchise locations within an eight-hour window during a regional heatwave week. For agencies serving home services, travel, retail, or hospitality clients, this is one of the few features on any platform that produces obvious incremental campaigns without manual segmentation work.

Where Moosend pushes back is on the integration list. Native connectors are limited compared to Mailchimp or HubSpot, and most third-party links route through Zapier, which adds a monthly subscription and a layer of latency. For agencies whose clients run a deep tool stack, the integration tax is real. For agencies whose clients run simple operations with a shop and a CRM, Moosend covers the requirements and leaves more margin on the table than any platform above it. The lack of a dedicated mobile app is the smaller annoyance. Account directors who like to approve campaigns from their phone on Sunday night will find the responsive web app workable but unloved.

If your agency books rate-card hours against e-commerce clients - Shopify stores in particular, but also BigCommerce, WooCommerce, and Magento - Klaviyo is the platform you should default to. We tested it against the regional e-commerce brand in our test roster, and the gap between Klaviyo and every other platform on this list was the widest single result of the four-week pilot. The Shopify integration installed in one click, pulled three years of historical purchase data within seven minutes, and made every order field available as a segmentation criterion before we built a single campaign.

For an agency standing up an e-commerce client from scratch, the pre-built flow library does roughly forty hours of setup work in an afternoon. Welcome series, abandoned checkout, browse abandonment, post-purchase, win-back, replenishment reminders, VIP segmentation - all available as templates we customized and deployed in our test client’s account within two days. The corresponding work in Mailchimp or ActiveCampaign would have taken a full sprint and required custom event tracking. For agencies that price retainer hours per project, this is the platform that lets you sell the same scope at a lower internal cost.

The revenue attribution dashboard is the feature that wins the retainer renewal. Every email campaign sent through Klaviyo gets attributed revenue at the order level, with clear logic for the attribution window and clear exclusion of organic search traffic from the count. When a client’s CEO asks at the quarterly review what the agency actually generated last quarter, the answer is a specific dollar figure pulled from a dashboard the client can also see, not a slide the agency built in PowerPoint with selected metrics. We have lost more retainer renewals to ambiguous attribution than to underperformance, and Klaviyo solves that problem more cleanly than anything else here.

The Partner Program is real but more competitive than HubSpot’s. Margin tiers start at 15 percent on referrals and scale based on certified agency rank, lead routing favors agencies with a track record and a partner manager, and the directory listing genuinely drives inbound for top-tier partners. For agencies whose Klaviyo book of business is already a meaningful share of revenue, formalizing the partnership is worth the certification effort.

The two things to know going in are the price and the design ceiling. Klaviyo is expensive once a client list crosses 50,000 active profiles, and the bill grows non-linearly with active SMS subscribers added. The template library is functional but no agency designer will be excited to work in it. For e-commerce agencies, neither limit is dealbreaking. For everyone else, this is the wrong tool, and the price difference compared to Brevo or Moosend is too large to ignore.

The thing to know about ActiveCampaign in an agency context is that the agency layer is the weakest part of an otherwise extraordinary product. The multi-account console works - you can spin up child accounts, attach permissions, and bill centrally - but next to Campaign Monitor’s purpose-built dashboard it feels like a feature that was added because the agency partnership team kept asking for it, not because the product was redesigned around it. Account switching costs a click and a half-second of loading where Campaign Monitor would have been instant. Reporting rolls up across clients but with less granularity than performance-focused agencies want. This is the platform’s clearest weakness for a reseller-first agency, and it is worth stating plainly before getting to anything else.

Set that aside, and what the platform does to the automation work that occupies most of an agency’s actual hours is harder to overstate. We rebuilt the same nurture sequence in all ten tools - new lead enters, downloads gated asset within seven days or gets a nudge, attends webinar or gets reminded, books a call or enters a re-engagement track - and ActiveCampaign was the only platform on this list that handled the full conditional tree without forcing us to chain three separate automations together. The Split Action node is the feature missing from every competitor that markets itself as “powerful automation.” It routes contacts down genuinely separate sequences based on real behavior, not just whether they opened an email.

For agencies serving B2B SaaS clients, the Site Tracking integration is the second piece worth flagging. We dropped the snippet on our synthetic SaaS client’s website, set up a rule that sent a personalized follow-up to anyone who viewed the pricing page twice in a week without booking a demo, and watched the first qualifying contact land in the segment within four minutes. That is the kind of automation that wins retainer renewals.

The reseller program is genuinely competitive. Margin tiers start at 20 percent on Plus plans and scale up to 30 percent for agencies hitting volume thresholds, with named partner managers and co-marketing budgets attached. The four-week deliverability average across our agency test list held at 95.8 percent for engaged segments. This is the most powerful automation builder on the list and the right choice for any agency whose senior strategists genuinely want to be in the platform rather than just delivering through it. The cost is the learning curve and the lag. Junior account managers will not pick this up in a week, and the canvas can take fifteen seconds to load once a flow gets dense. Agencies that staff for it are rewarded. Agencies that do not are better off one tier lower.

If you run a B2B agency whose clients are mid-market SaaS companies, services firms, or consultancies with a defined sales motion, HubSpot Marketing Hub is the platform you should evaluate first. That sentence is the entire pitch, and it is also the limit. We tested HubSpot against the B2B SaaS startup in our test client roster - the one with nurture flows tied to product behavior - and the platform handled the brief so naturally it felt as if the brief had been written from inside HubSpot’s own product roadmap. We built a nurture sequence that triggered off pipeline-stage changes in the CRM, fed sales reps a notification when a lead opened a specific pricing-page link, and routed unconverted leads back into a re-engagement workflow at the 60-day mark. None of that required a third-party integration or a webhook hack.

For the same exact agency working with our regional e-commerce brand, HubSpot was the wrong tool. The catalog connector is functional but not native in the way Klaviyo’s is. The cost of Professional-tier features per client account became prohibitive once we modeled what the e-commerce client would pay versus what they would actually use. This is the platform’s tell: HubSpot is built for the client whose entire business runs through a sales funnel. Agencies serving those clients - and there are a lot of them - get a tool with no real competitor in its lane. Agencies trying to use HubSpot for clients outside that lane will spend half their retainer hours apologizing for features the client is paying for and not using.

The Solutions Partner program is where the agency math gets interesting. HubSpot pays partners on a recurring revenue share that can reach 20 percent of client subscriptions, with tiered benefits and a dedicated channel team attached. For agencies whose business model includes platform implementation as a service, this is structural revenue, not a side benefit. Our team’s experience over multiple past partner engagements is that the program works as advertised and the channel team responds within hours, not days.

Reporting handoff is the other place HubSpot quietly wins. Read-only client portals work, scheduled report exports work, and the attribution model is detailed enough to defend a retainer at a quarterly board review. The pricing wall is the offset. For an agency with three Professional-tier clients and three Starter-tier clients, the bill arrives meaningful. HubSpot is the right call for the B2B side of an agency’s book and the wrong call for everything else, and that division is sharper here than on any other platform we tested.

The first thing that happened when we opened Mailchimp for the local services franchise in our test roster was a junior strategist saying, “Oh good, this one I know.” That single sentence is most of why agencies still use Mailchimp despite every reason not to. Half the marketing-adjacent humans on your team have already used it at a previous job, and the onboarding tax that exists in Campaign Monitor or ActiveCampaign or HubSpot effectively does not exist here. We had a full welcome series built for the franchise client in under three hours, including a campaign-style header image generated by Creative Assistant from a single brand-color upload.

The second thing that happened was the bill estimate for running all six client accounts came back high. Mailchimp counts every contact toward the billable total - including unsubscribed addresses, until you manually archive them - and the agency math gets uncomfortable fast. We checked the aggregate contact count across our six synthetic clients on day three and found 1,400 unsubscribed addresses still being billed. After archiving them, the projected monthly cost dropped 18 percent. This is the kind of invisible margin leak that agencies should audit on every Mailchimp account they inherit. The clients who came in pre-set-up almost always have it.

The third thing that happened was the franchise client’s regional manager asked for a campaign in 90 minutes for a same-day store reopening, and Mailchimp produced it. The drag-and-drop editor remains the best in the category for non-designers producing visually credible work at speed. For agencies serving small-business clients who measure agency value in how quickly a campaign can be deployed when the client calls in a panic, Mailchimp’s editor justifies the platform regardless of its limitations elsewhere. The Creative Assistant in particular is the feature most agencies underuse. Upload a logo, set two brand colors, and the system generates header graphics, social cards, and product blocks that pass a junior designer’s eye test without anyone touching Photoshop.

The fourth and last thing that happened was an automation request from the SaaS client that Mailchimp could not handle elegantly. The Customer Journey builder works for linear flows. Set it against ActiveCampaign’s Split Action paths and it falls behind the moment a sequence needs to branch on more than one behavior. Deliverability across the four-week pilot averaged 96.1 percent for engaged segments, which is solid but not industry-leading. For agencies whose client roster skews to small businesses needing visually credible newsletters and basic automation, Mailchimp is a defensible pick. For agencies serving clients whose automation requirements have outgrown linear flows, it is not.

The deal-breaker has to come first. Constant Contact’s automation is genuinely simplistic by 2026 standards. The builder handles linear sequences cleanly - welcome series, birthday emails, post-purchase follow-ups - but the moment a client brief requires branching based on behavior, the platform falls short. Set it against ActiveCampaign’s Split Action or even Mailchimp’s Customer Journey builder and the gap is immediate. For agencies whose client roster requires meaningful behavioral automation, this is the wrong platform and the rest of the review is academic.

For everyone else, the platform earns its position through a set of features almost no competitor takes seriously anymore. Live phone support is the obvious one. Our team called the agency partner line three times during the four-week pilot - once with a deliverability question, once with a billing query, once with a deliberately tricky API question to test depth - and got a human within four minutes on the first two calls and within twelve on the third. For an agency account director whose junior strategist is panicking about a Friday-afternoon campaign that will not render correctly on Outlook, this is not a minor benefit. It is the difference between a recoverable hour and a Saturday phone call to the client.

The event management features are the second underrated piece. For agencies serving nonprofits, education, local services, or any client whose marketing calendar revolves around events - fundraisers, community days, store openings, webinars - Constant Contact’s built-in registration, ticketing, and follow-up flows handle the work other platforms require a third-party tool to cover. We built a full fundraising gala flow for our nonprofit test client in two hours: invitations, ticket purchase, attendee reminders, post-event thank-you, donor segmentation. The corresponding work in Mailchimp would have required Eventbrite, Zapier, and a string of custom audience filters.

The platform’s biggest structural weakness for agencies is the multi-account model. Constant Contact does not have a meaningful agency dashboard the way Campaign Monitor does. Most agencies end up running one account per client, paying per-account, and reconciling billing manually. Account cancellation requiring a phone call is the second ops headache. When an agency loses a client and tries to wind down the corresponding Constant Contact account from email or chat, the platform routes the cancellation to a retention phone queue, which adds friction at the worst possible moment. Deliverability over the four-week pilot averaged 96.2 percent, which is consistent and unsurprising for a platform whose reputation is built on stability rather than innovation. Pick Constant Contact if your agency runs on small-business clients with event-heavy calendars. Look elsewhere for almost any other agency profile.

MailerLite makes this list because of how little it asks of an agency operations team. The standout feature is the absence of friction: load times, editor response, navigation logic, and billing flow all behave as a small agency would want them to behave, with no negotiation. Our team timed the editor load against the other nine platforms during the four-week pilot, and MailerLite’s average from click to fully interactive came in at 0.7 seconds compared to a list median of 2.1 seconds. For an agency strategist building twenty campaigns in a busy week, the cumulative time difference is measurable and morale-relevant.

The per-site sub-account model is the second feature that earns the position. Rather than building a complex agency dashboard, MailerLite simply lets agencies stand up a separate account per client at a discounted partner rate. For lean two- and three-person agencies, this is the right architecture. There is no central console to learn, no permission model to debug, no inheritance rules to manage. Each client account is its own world. Billing rolls up to a partner master account. We onboarded all six of our test client workspaces in a single afternoon, including custom sending domains and verified DNS records, and the next morning every account was ready to send.

The drag-and-drop editor matches Mailchimp for visual quality and beats it for code cleanliness. Emails built in MailerLite render predictably across Outlook 2016, Outlook 365, the Gmail web client, the Gmail mobile app, and the standard iOS Mail client. We sent the same campaign through all ten platforms to a controlled inbox set and MailerLite was one of three platforms that produced zero rendering issues across the test matrix. For agencies whose clients still send a meaningful share of email to corporate Outlook addresses - and that is most B2B clients - this is a feature that prevents an entire category of post-send embarrassment.

Where MailerLite pushes back is on imports and automation. The approval process for new accounts is genuinely strict, and our test account took 36 hours to clear initial review despite a clean import. Agencies onboarding a client with an inherited list should expect a review delay every time. The other limit is on automation depth. The visual workflow builder is competent for welcome series, birthday flows, and post-purchase sequences, but the moment branching logic gets dense the platform forces simplifications that ActiveCampaign would not. For agencies serving creator-economy clients, small e-commerce brands, and consultants - the kind of clients whose automation needs are real but bounded - MailerLite remains the most pragmatic pick on this list.

SendGrid is the platform on this list with the narrowest agency fit and the most defensible reason for it. Compared to every other tool in this review, SendGrid is the only one whose value proposition rests on serving both the marketing team and the engineering team from a single account. For agencies whose client roster includes SaaS companies, fintech startups, or any product with a real transactional email volume - password resets, receipts, account verifications, in-app notifications - SendGrid lets the agency deliver both the campaign work and the transactional infrastructure on one platform.

Set SendGrid against Brevo, which also offers transactional plus marketing in one tool, and the comparison gets specific. Brevo wins on cost, on the cleanness of its marketing UI, and on the breadth of channels (SMS and WhatsApp included). SendGrid wins on scale, on the depth of its developer ecosystem, and on the maturity of its deliverability tooling at high volume. For our synthetic agency profile with six clients, none of whom were sending more than 100,000 transactional emails per month, Brevo was the better pick. For an agency taking on a SaaS client sending 5 million transactional emails per month, SendGrid is the only tool here that handles the volume without requiring a separate infrastructure provider.

The sub-user architecture is the agency-relevant feature. SendGrid lets agencies provision separate sub-users per client, each with isolated sending domains, IP pools, and template libraries, all administered from one parent account. We set up six sub-users for our test clients in under an hour and configured isolated DKIM and SPF records for each. The administrative work was heavier than Campaign Monitor’s agency dashboard but lighter than running six separate Mailchimp accounts.

Where the platform is weakest is on the marketing-side experience. The campaign builder, design templates, and analytics dashboards all feel like a tool built for engineers who occasionally have to send a marketing email, rather than a tool built for marketers from the start. Compared to Klaviyo’s revenue dashboards or HubSpot’s attribution models, SendGrid’s marketing reporting is informational at best. The support quality issue is the second concern. Multiple agency operators we have spoken to over the past year report that lower-tier SendGrid support has degraded to canned responses and long delays. For agencies whose business depends on quick platform support during campaign-week emergencies, this is a real risk that is hard to test until it matters. SendGrid earns its place on this list as a specialist tool. Agencies whose clients need it will know who they are. Agencies whose clients do not need it should not pick it on principle.