It is notoriously difficult to obtain reliable customer data for email service providers.
In one of my more popular LinkedIn posts, which got over 6,000 impressions, I tried to come up with a ranking based on Datanyze data.
However, the data felt a bit…wonky.
LinkedIn post on email provider market share
For example, who has ever heard of AcyMailing? And why are Brevo and ActiveCampaign missing from this list?
To create a more realistic ranking, I tried to find the data the ESPs publish themselves about their user numbers. Fortunately, almost all the SMB-focussed email service providers publish some sort of user data.
The 20 Most Popular ESPs and Their Hypothetical Market Share
Based on the latest self-reported data, here's a breakdown of the user numbers and (hypothetical) market share for the top ESPs:
| Rank | ESP | Number of Users (2024) | Number of Users (2026) | Change | Market Share (Hypothetical) | Country | Source | Comment |
|---|---|---|---|---|---|---|---|---|
| 1 | Mailchimp | 11,000,000 | 11,000,000 | 0 | 65.76% | USA | Mailchimp website | “11 million businesses use Mailchimp.” |
| 2 ↑ | MailerLite | 658,530 | 1,000,000 | +52% | 5.98% | USA / Lithuania | MailerLite website | “Join 1M+ creators and businesses“ |
| 3 | Constant Contact | 650,000 | 650,000 | 0 | 3.89% | USA | Constant Contact press release | “The company helps more than 650,000 customers.” |
| 4 ↑ | Kit | 56,513 (real customers) | 640,000 | N/A | 3.83% | USA | Kit website | “used by Tim Ferriss, Andrew Huberman, and more than 640,000 other creators“ |
| 5 ↑ | Brevo | 500,000 | 600,000 | +20% | 3.59% | France | Brevo website | “600K Customers globally” |
| 6 | GetResponse | 400,000 | 400,000 | 0 | 2.39% | Poland | GetResponse website | “400,000+ customers worldwide” |
| 7 ↑ | CleverReach | 370,000 | 400,000 | +8.1% | 2.39% | Germany | CleverReach website | “400,000 customers from over 170 countries” |
| 8 ↑ | Hubspot | 216,000 | 278,000 | +29% | 1.66% | USA | HubSpot Newsroom | “Today, over 278,000 customers” (Includes non email marketing customers) |
| 9 | Campaign Monitor | 250,000 | 250,000 | 0 | 1.49% | Australia | Campaign Monitor website | “250,000 companies worldwide love Campaign Monitor.” |
| 10 ↑ | rapidmail | 200,000 | 250,000 | 0 | 1.49% | Germany | rapidmail website | “Und zwar ein Tool, mit dem schon über 250.000 Unternehmen” |
| 11 | Keap | 205,600 | 205,600 | 0 | 1.23% | USA | Keap website | “205.6 K Users” (31.5K customers) |
| 12 ↑ | Klaviyo | 143,000 | 183,000 | +28% | 1.09% | USA | Klaviyo investor report | “183K+ Customers.” |
| 13 ↑ | ActiveCampaign | 150,000 | 180,000 | +20% | 1.08% | USA | ActiveCampaign website | “See how 180k+ customers are growing” |
| 14 ↑ | Omnisend | 100,000 | 150,000 | +50% | 0.90% | Lithuania | Omnisend website | “150,000+ Online stores use Omnisend to grow their businesses” |
| 15 ↑ | Email Octopus | 83,000 | 100,000 | +19% | 0.60% | UK | Email Octopus website | “we’ve now helped over 100,000 users feel like instant marketing pros” |
| 16 (new) | Moosend | – | 100,000 | N/A | 0.60% | Greece/UK | Moosend home page | “Join 100,000+ empowered customers“ |
| 17 ↓ | Benchmark | 500,000 | 100,000 | N/A | 0.60% | USA | Benchmark Email website | “More than 100,000 marketers worldwide rely on Benchmark Email” |
| 18 | AWeber | 100,000 | 100,000 | 0 | 0.60% | USA | AWeber website | “AWeber is an email marketing service provider helping over 100,000 customers.” |
| 19 | Campaigner | 100,000 | 100,000 | 0 | 0.60% | USA | Campaigner website | “over 100,000 businesses“ |
| 20 | Mailjet | 40,000 | 40,000 | 0 | 0.24% | France | Mailjet website | “With over 40,000 customers in 150 countries” |
Data originally collected in June 2024. Updated in January 2026.
Similar to the Datanyze data I shared on LinkedIn, Mailchimp is still dominating the email marketing market by sheer user numbers. They were one of the first platforms to popularize a freemium plan, which likely played a major role in their growth. That said, it’s still unclear how many of these users actually pay.
MailerLite is another ESP that offers a generous free plan. Between 2024 and 2026, it saw massive growth of 52% and is now serving over 1 million users.
Constant Contact didn’t grow during this period, but appears to have held steady at 650,000 customers. If these are mostly paid accounts, that level of retention would be impressive.
Kit changed how they publish their data. They previously shared a Baremetrics dashboard showing their real customer base and revenue, but this is no longer public. Instead, Kit now reports a user count of 640,000. Given how attractive its free tier is, it’s likely that a large share of those users are not paying customers.
Brevo saw healthy growth of 20% compared to 2024 and now serves more than 600,000 customers.
One of the more surprising names here is CleverReach, which isn’t widely known internationally. It’s likely the biggest ESP in German-speaking countries (Germany, Austria, and Switzerland) and now claims 400,000 customers, putting it on par with GetResponse.
rapidmail is another ESP that is big in the German-speaking markets, now reaching an impressive 250,000 customers.
More expensive ESPs like Klaviyo (+28%) and ActiveCampaign (+20%) saw their customer bases increase significantly. While they don’t match the user numbers of the more popular ESPs, it’s fair to assume their margins are considerably higher.
Omnisend, often positioned as Klaviyo’s main competitor, grew by 50% and now serves 150,000 online stores.
Limitations of the data
It's important to note that the data comes from the websites of the ESPs themselves. While this is the best data available, it should be taken with a grain of salt. The companies use different terms to describe their users. Some call it “users,” others “customers,” or “companies”, which can sometimes be misleading. A “user” or a “company” doesn't always pay for the service if there's a free tier available. A customer, on the other hand, indicates that money is being exchanged.
Unfortunately, we weren't able to find good data for Moosend, Drip or SendPulse. Moosend says, “Moosend is used by thousands of businesses”. We couldn't find any data for Drip. And SendPulse says this: “SendPulse reached 3 million registered users, with more than 1,000 new users joining daily”, which seems unrealistically high, given their relatively small brand. Neither Google search volumes (based on Ahrefs) nor other data sources (e.g. Datanyze) indicate a high popularity that is that high.
The market share number you find in the table is hypothetical. It's based on user/customer numbers and doesn't reflect a monetary value. If sales were taken into account, players like Salesforce, Listrak or SAP emarsys might play a much bigger role.
Conclusion: An Accurate Picture of the Email Provider Market Share?
Based on all the data sources available, using the ESP's self-reported data seems most reliable.
Mailchimp continues to dominate the market with a significant lead, boasting over 11 million users. Other providers like MailerLite, Constant Contact, Kit and Brevo also have substantial user bases, but they lag behind Mailchimp's impressive numbers.
When choosing an ESP, it's essential to consider not just the number of users but also the specific features and capabilities that meet your business needs. That's where we come in:
> Compare the best email marketing services
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07 Jan 2026 – Table completely updated with 2026 data
09 Jul 2024 – Campaigner added, other small corrections
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This article has been written and researched following our EmailTooltester methodology.
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