Email marketing tools help businesses send newsletters, promotional offers, and automated messages to their customers. A small group of software companies make most of the email marketing platforms used by American businesses today.

Some of these companies started as small side projects in Atlanta, Massachusetts, and Chicago. Others came from Poland and France before growing into tools used by businesses across the United States.

In this article, we’ll discuss the top 10 email marketing tools used in the United States, based on their history, ownership, and the kind of businesses they are known for serving.

Quick Comparison

Rank	Company	Founded	Owner / Founders	US Headquarters	Core Focus
1	Mailchimp	2001	Founded by Ben Chestnut & Dan Kurzius; owned by Intuit, led by CEO Rania Succar	Atlanta, Georgia	Small Business Email Marketing
2	Constant Contact	1995	Founded by Randy Parker; owned by Clearlake Capital, led by CEO Frank Vella	Waltham, Massachusetts	Small Business & Nonprofit Email
3	Klaviyo	2012	Founded by Andrew Bialecki & Ed Hallen; publicly listed, led by CEO Andrew Bialecki	Boston, Massachusetts	E-commerce Email & SMS Marketing
4	ActiveCampaign	2003	Founded by Jason VandeBoom; privately held, led by CEO Jason VandeBoom	Chicago, Illinois	Email & Marketing Automation
5	SendGrid	2009	Founded by Isaac Saldana, Jose Lopez & Tim Jenkins; part of Twilio	Denver, Colorado	Transactional & Bulk Email Delivery
6	Campaign Monitor	2004	Founded by Ben Richardson & Dave Greiner; part of CM Group	Nashville, Tennessee	Design-Focused Email Marketing
7	AWeber	1998	Founded by Tom Kulzer; privately held, led by CEO Tom Kulzer	Chalfont, Pennsylvania	Small Business Email Automation
8	GetResponse	1998	Founded by Szymon Grabowski; privately held, led by CEO Szymon Grabowski	Gdansk, Poland (US operations)	All-in-One Marketing Platform
9	Brevo (formerly Sendinblue)	2012	Founded by Armand Thiberge & Kapil Sharma; led by CEO Armand Thiberge	Paris, France (US operations)	Email, SMS & CRM Platform
10	HubSpot Marketing Hub	2006	Founded by Brian Halligan & Dharmesh Shah; publicly listed, led by CEO Yamini Rangan	Cambridge, Massachusetts	Inbound Marketing & Email

1. Mailchimp – A Bootstrapped Startup That Sold for $12 Billion

• Founded: 2001 
• Owner: Founded by Ben Chestnut & Dan Kurzius; owned by Intuit, led by CEO Rania Succar 
• Headquarters: Atlanta, Georgia

Mailchimp started in 2001 as a side project by Ben Chestnut and Dan Kurzius, who were running a web design business at the time. The two noticed small business clients needed an easy way to send email newsletters, so they built a tool to help. They didn’t commit to it full time until 2007, once enough customers started paying for the service.

Chestnut and Kurzius famously built Mailchimp without ever taking outside investor money, an unusual feat for a company this size. In 2021, financial software company Intuit bought Mailchimp for $12 billion, one of the largest acquisitions ever of a bootstrapped company. Rania Succar now leads Mailchimp as CEO under Intuit’s ownership.

What Mailchimp does: Helps small businesses create and send email newsletters and marketing campaigns.

Services: Email newsletters, marketing automation, landing pages, and audience segmentation tools.

2. Constant Contact – One of the Oldest Names in Email Marketing

• Founded: 1995 
• Owner: Founded by Randy Parker; owned by Clearlake Capital, led by CEO Frank Vella 
• Headquarters: Waltham, Massachusetts

Constant Contact began in 1995 under the name Roving Software, started by Randy Parker after he noticed small businesses lacked the digital marketing tools that large companies took for granted. Gail Goodman joined as CEO in 1999, well before the company had a finished product, and helped shape it into a leading email marketing platform. The business officially adopted the Constant Contact name in 2004.

The company went public in 2007 and later sold to web hosting company Endurance International in 2015. Private equity firm Clearlake Capital bought the business in 2021, and Frank Vella took over as CEO that same year. Constant Contact remains especially popular among small businesses and nonprofit organizations.

What Constant Contact does: Provides email and multi-channel marketing tools for small businesses and nonprofits.

Services: Email marketing, SMS campaigns, event marketing, and social media posting tools.

3. Klaviyo – An E-commerce Email Tool Built by a Physicist

• Founded: 2012 
• Owner: Founded by Andrew Bialecki & Ed Hallen; publicly listed, led by CEO Andrew Bialecki 
• Headquarters: Boston, Massachusetts

Klaviyo was started in 2012 by Andrew Bialecki, a Harvard-trained engineer and physicist, along with co-founder Ed Hallen. The two built their platform specifically around online stores, connecting directly with e-commerce platforms like Shopify to track customer purchase behavior. This deep integration let Klaviyo send highly targeted emails based on what shoppers actually bought or browsed.

Bialecki bootstrapped the company for years before eventually taking outside investment to fuel faster growth. Klaviyo went public in 2023, with Bialecki retaining an unusually large ownership stake for a founder at IPO. The company has grown quickly into one of the top email and SMS tools for online retailers.

What Klaviyo does: Helps online stores send targeted email and SMS marketing based on customer behavior.

Services: E-commerce email marketing, SMS campaigns, customer data tracking, and personalized automation.

4. ActiveCampaign – A Marketing Platform Funded by Freelance Consulting

• Founded: 2003 
• Owner: Founded by Jason VandeBoom; privately held, led by CEO Jason VandeBoom 
• Headquarters: Chicago, Illinois

ActiveCampaign was started in 2003 by Jason VandeBoom, a self-taught software engineer who originally built the company to help pay for his fine arts degree. He ran the business as a side hustle for years, taking on consulting work to keep it afloat before switching focus entirely. VandeBoom combined email marketing with automation, sales, and basic CRM features into one platform.

The company grew entirely through its own profits for its first several years, without raising any outside investment. ActiveCampaign eventually took on funding to expand faster, reaching unicorn status with a billion-dollar valuation in 2021. Jason VandeBoom still leads the company today as founder and CEO.

What ActiveCampaign does: Combines email marketing with automation and basic CRM tools for growing businesses.

Services: Email marketing, marketing automation, sales CRM, and customer experience tracking.

5. SendGrid – A Developer-Focused Tool Now Owned by Twilio

• Founded: 2009 
• Owner: Founded by Isaac Saldana, Jose Lopez & Tim Jenkins; part of Twilio 
• Headquarters: Denver, Colorado

SendGrid was started in 2009 by three University of California, Riverside engineers who had grown frustrated with unreliable email delivery for their own web projects. Isaac Saldana, Jose Lopez, and Tim Jenkins built SendGrid specifically for developers who needed a dependable way to send emails from their own apps and websites. This technical, developer-first approach set SendGrid apart from more marketing-focused competitors.

The company went public on the New York Stock Exchange in 2017. Just two years later, communications company Twilio bought SendGrid in a $2 billion all-stock deal, folding it into its broader platform. SendGrid continues operating as part of Twilio, with its website fully merging into Twilio.com starting in 2026.

What SendGrid does: Helps developers and businesses reliably send transactional and marketing emails.

Services: Email delivery infrastructure, marketing campaign tools, and email deliverability monitoring.

6. Campaign Monitor – An Australian Startup That Found Its Home in Nashville

• Founded: 2004 
• Owner: Founded by Ben Richardson & Dave Greiner; part of CM Group 
• Headquarters (US): Nashville, Tennessee

Campaign Monitor was started in 2004 by two childhood friends from Sydney, Australia, Ben Richardson and Dave Greiner, who built the tool part-time while running a separate web design business. Their first version was built specifically for web developers comfortable writing HTML and CSS code. The product slowly evolved into an easier, design-focused tool for marketers without technical skills.

The company grew steadily, eventually serving well-known brands like Coca-Cola and Disney for their email campaigns. Campaign Monitor later became part of CM Group, a collection of marketing software brands with US headquarters in Nashville, Tennessee. The platform remains especially known for its clean, design-friendly email templates.

What Campaign Monitor does: Provides design-focused email marketing tools for businesses and agencies.

Services: Email marketing, automation workflows, and customizable email templates.

7. AWeber – A Bootstrapped Tool Built for Small Business Owners

• Founded: 1998 
• Owner: Founded by Tom Kulzer; privately held, led by CEO Tom Kulzer 
• Headquarters: Chalfont, Pennsylvania

AWeber was started in 1998 by Tom Kulzer, who built the company specifically to help small businesses communicate more effectively with customers through permission-based email. Kulzer grew the business from zero revenue into a company serving well over 100,000 active clients over the following decades. Unlike many competitors, AWeber never raised outside venture capital funding.

The company stayed privately held and profitable, focusing mainly on simple, affordable tools for small business owners rather than large enterprises. Tom Kulzer continues to lead AWeber today as founder and CEO. The platform remains especially popular among solo entrepreneurs and small marketing teams.

What AWeber does: Provides simple, affordable email marketing tools for small businesses.

Services: Email automation, landing pages, sign-up forms, and basic e-commerce integrations.

8. GetResponse – A Polish Teenager’s Email Tool Gone Global

• Founded: 1998 
• Owner: Founded by Szymon Grabowski; privately held, led by CEO Szymon Grabowski 
• Headquarters: Gdansk, Poland (US operations)

GetResponse traces back to 1996, when a 17-year-old Polish entrepreneur named Szymon Grabowski started experimenting with online tools using just $200 in savings. After an early partnership fell apart, Grabowski rebuilt the product from scratch and launched GetResponse in 1998. He grew the company into one of the largest email marketing platforms in the world, entirely funded by its own profits.

GetResponse expanded over the years to include marketing automation, website building, and webinar hosting alongside its core email tools. The company opened international offices, including one in Halifax, Canada, to better serve customers in North America. Grabowski still leads the company today as founder and CEO.

What GetResponse does: Provides an all-in-one marketing platform centered around email marketing.

Services: Email marketing, marketing automation, website building, webinars, and conversion funnels.

9. Brevo (formerly Sendinblue) – A French Platform Pushing Into the US Market

• Founded: 2012 
• Owner: Founded by Armand Thiberge & Kapil Sharma; led by CEO Armand Thiberge 
• Headquarters (US operations): Paris, France

Brevo started in Paris in 2012 under the name Sendinblue, founded by Armand Thiberge and Kapil Sharma, with engineering teams based in both France and India. The company built its platform around affordable, all-in-one marketing tools aimed at small and mid-sized businesses. Email marketing formed the original core of the product before the company expanded into SMS, chat, and basic CRM features.

In 2023, the company rebranded from Sendinblue to Brevo, reflecting its growth beyond simple email newsletters. Brevo raised a large funding round in late 2025, reaching unicorn status with a valuation over $1 billion. The United States now represents about 15 percent of Brevo’s revenue, with the company actively investing in further US growth.

What Brevo does: Provides an all-in-one platform combining email, SMS, and basic CRM tools.

Services: Email marketing, SMS campaigns, WhatsApp messaging, and customer relationship management.

10. HubSpot Marketing Hub – An MIT Project That Grew Into a Marketing Giant

• Founded: 2006 
• Owner: Founded by Brian Halligan & Dharmesh Shah; publicly listed, led by CEO Yamini Rangan 
• Headquarters: Cambridge, Massachusetts

HubSpot was started in 2006 by Brian Halligan and Dharmesh Shah, two graduate students who met at MIT and noticed customers were growing tired of being interrupted by ads and cold calls. They built their platform around “inbound marketing,” helping businesses attract customers with helpful content instead of constant interruptions. Email marketing became one of the core tools within this broader approach.

The company grew into a full marketing, sales, and customer service platform rather than just an email tool. Brian Halligan stepped back from daily leadership in 2021, handing the CEO role to Yamini Rangan, who had joined as chief customer officer. HubSpot’s Marketing Hub remains especially popular among small and mid-sized businesses looking for an all-in-one marketing solution.

What HubSpot Marketing Hub does: Combines email marketing with broader content marketing and automation tools.

Services: Email marketing, landing pages, marketing automation, and content management tools.

Frequently Asked Questions (FAQs)

1. Which is the most widely used email marketing tool in the USA?

Mailchimp is widely considered one of the most popular email marketing tools in the country, especially among small businesses.

2. Which email marketing companies are still privately held rather than publicly traded?

ActiveCampaign, AWeber, and GetResponse all remain privately held, built mostly through their own profits rather than outside investment.

3. Which company is best known for serving e-commerce and online stores?

Klaviyo is best known for serving e-commerce businesses, with deep integration into platforms like Shopify.

4. Which company was sold for $12 billion despite never taking outside funding?

Mailchimp was sold to Intuit for $12 billion in 2021, despite its founders never taking outside investor money.

5. Which company is now owned by Twilio?

SendGrid is now owned by Twilio, which bought the email delivery company in a $2 billion deal in 2019.

6. Which company started as an Australian side project?

Campaign Monitor started as a side project by two childhood friends from Sydney, Australia, before later establishing US headquarters in Nashville.

7. Are email marketing tools in the USA regulated?

Yes, email marketing companies must follow federal rules like the CAN-SPAM Act, which sets requirements for commercial email messages.

8. Which company was founded by a teenager with just $200?

GetResponse was founded by Szymon Grabowski, who started experimenting with the idea as a 17-year-old with only $200 in savings.

9. Which company recently reached unicorn status after a major funding round?

Brevo reached unicorn status in late 2025 after raising $583 million in a funding round valuing the company above $1 billion.

10. Why do these ten companies matter to everyday businesses?

These companies provide the tools that millions of American businesses use to stay in touch with customers through email and related channels.

Conclusion

The United States email marketing industry is home to bootstrapped startups, MIT projects, and international platforms, all vying for business. Mailchimp, Constant Contact, Klaviyo, ActiveCampaign, SendGrid, AWeber, and HubSpot are companies which either built or supported large-scale operations from the soil of the U.S., while Campaign Monitor, GetResponse, and Brevo represent Australian, Polish, and French expertise in marketing software respectively.

These ten companies supply the U.S. market with email marketing services used by thousands of businesses, both big and small, to communicate with their customers. As the U.S. continues to lead the pack in automation and personalization, these companies are set to play a significant role in the way American businesses connect with their consumers.