Historical Aspect of SendGrid vs Mailjet: Transactional Email Services Compared

The evolution of transactional email services is closely tied to the broader history of cloud computing, SaaS platforms, and developer-centric infrastructure. Before platforms like SendGrid and Mailjet emerged, businesses relied heavily on in-house mail servers or generic SMTP providers, which were often unreliable, difficult to scale, and prone to deliverability issues.

The rise of APIs, cloud infrastructure, and software-as-a-service (SaaS) in the late 2000s and early 2010s created the conditions for specialized email delivery companies to thrive. Among these, SendGrid and Mailjet stand out as two influential platforms that helped shape modern transactional email ecosystems. Although both serve similar purposes today, their historical development paths reflect different origins, philosophies, and market strategies.

This article explores the historical evolution of SendGrid and Mailjet, comparing how each platform developed, scaled, and positioned itself in the global email infrastructure market.

1. The Origins of SendGrid

SendGrid was founded in 2009 in Denver, Colorado by Isaac Saldana, Jose Lopez, and Tim Jenkins. The company emerged during a period when startups were rapidly adopting cloud-based infrastructure and needed reliable ways to send emails at scale. Traditional SMTP servers were no longer sufficient for modern web applications, particularly those requiring automated emails such as password resets, account verifications, and notifications.

From the beginning, SendGrid was built with a developer-first philosophy. The founders aimed to create a service that “just worked” for developers, eliminating the complexity of managing email servers. According to its early vision, SendGrid sought to abstract email delivery into a simple API layer that could be integrated into any application.

Early Growth Phase (2009–2013)

SendGrid’s early growth was fueled by the increasing demand for cloud applications and SaaS platforms. Key milestones include:

• Participation in the Techstars accelerator program
• Early funding rounds from venture capital firms like Foundry Group and Bessemer Venture Partners
• Rapid adoption by startups needing scalable email infrastructure

By 2010–2012, SendGrid had already positioned itself as a leading email delivery API provider, focusing heavily on transactional email use cases such as shipping notifications, signup confirmations, and system alerts.

During this period, SendGrid also expanded into marketing email services, broadening its platform beyond purely transactional messaging. This diversification helped it compete with emerging marketing automation tools.

Expansion and IPO (2013–2017)

As cloud adoption accelerated globally, SendGrid experienced significant growth. It expanded its infrastructure, improved deliverability systems, and strengthened its API offerings.

By 2017, SendGrid went public on the New York Stock Exchange, marking a major milestone in its evolution from startup to established cloud communications provider. This IPO reflected investor confidence in email APIs as a core component of digital infrastructure.

At this stage, SendGrid had already become a global-scale email delivery platform, processing billions of emails monthly and serving tens of thousands of customers worldwide.

Acquisition by Twilio (2018–2019)

One of the most defining moments in SendGrid’s history was its acquisition by Twilio in 2018 for approximately $2 billion, completed in early 2019.

This acquisition was strategically important because Twilio had built its reputation in SMS, voice, and messaging APIs—but lacked an email solution. SendGrid filled that gap, enabling Twilio to become a full omnichannel communications platform covering:

• SMS
• Voice
• Chat apps
• Video
• Email

This integration marked the transition of SendGrid from an independent company to a core component of a larger communications ecosystem.

2. The Origins of Mailjet

Mailjet was founded in 2010 in Paris, France, just one year after SendGrid. Its founders, Wilfried Durand and Julien Tartarin, launched the company with a slightly different vision: making email not only programmable but also collaborative and accessible to non-developers.

While SendGrid focused heavily on developers and API-first architecture, Mailjet aimed to bridge the gap between developers and marketing teams.

Early Development (2010–2014)

Mailjet’s early growth was supported by European venture capital funding and startup studio eFounders. The company positioned itself around three core ideas:

• Simplifying email creation
• Enabling collaboration between teams
• Offering both transactional and marketing email in one platform

Unlike SendGrid, which initially targeted developers, Mailjet deliberately built tools for mixed audiences, including marketers, designers, and product teams.

During this period, Mailjet expanded across Europe and later into the United States, opening offices in major cities such as New York and London.

Scaling and International Growth (2014–2018)

Between 2014 and 2018, Mailjet experienced steady international growth. It raised additional funding rounds and expanded its customer base across multiple continents. By 2015, it had tens of thousands of customers globally.

A key historical differentiator during this period was Mailjet’s focus on collaborative email editing, a feature that allowed multiple team members to work on email campaigns in real time. This innovation set it apart from many competitors, including SendGrid, which remained more developer-centric.

Mailjet also strengthened its transactional email API, positioning itself more directly against SendGrid in the same market segment.

Acquisition and Integration into Sinch (2019–2021)

Mailjet’s major turning point came in 2019 when it was acquired by Mailgun, another email API provider. Later, in 2021, Mailgun’s parent company Pathwire was acquired by Sinch, a Swedish cloud communications company.

This integration placed Mailjet within a broader communications ecosystem similar to Twilio’s acquisition of SendGrid. Both platforms became part of larger “communications platform as a service” (CPaaS) ecosystems.

3. Diverging Philosophies in Early Development

Although SendGrid and Mailjet were founded only a year apart, their historical trajectories reflect different philosophies:

SendGrid: Developer-Centric Infrastructure

SendGrid’s early identity was rooted in solving a technical problem: reliable email delivery at scale. Its architecture, APIs, and tooling were designed primarily for engineers building web applications.

Key historical traits:

• API-first design
• Focus on deliverability and scale
• Early adoption by startups and SaaS companies
• Strong emphasis on infrastructure reliability

Mailjet: Collaboration and Accessibility

Mailjet, on the other hand, focused on making email accessible to broader teams, not just developers.

Key historical traits:

• Emphasis on UI and collaboration tools
• Unified marketing + transactional platform
• Strong appeal to SMEs and marketing teams
• European compliance-driven development (GDPR focus later on)

4. Market Evolution and Competitive Convergence

Over time, both platforms began converging toward similar capabilities:

• SendGrid expanded into marketing automation
• Mailjet strengthened its transactional API capabilities

This convergence reflects a broader industry trend: the blending of transactional email (system-driven) and marketing email (campaign-driven) into unified communication platforms.

By the late 2010s, both companies were competing not just with each other, but also with emerging platforms like Amazon SES, Postmark, and Mailgun.

5. Impact of Acquisitions on Historical Trajectories

The acquisitions of both companies significantly shaped their historical identity:

SendGrid under Twilio

After acquisition, SendGrid became part of a larger ecosystem that unified multiple communication channels. This shifted its role from standalone email provider to a component in omnichannel communication infrastructure.

Mailjet under Sinch

Similarly, Mailjet’s integration into Sinch positioned it within a European-led communications network, emphasizing compliance, scalability, and integration with other messaging services.

6. Historical Significance in the Email Ecosystem

From a historical perspective, SendGrid and Mailjet represent two parallel approaches to solving the same problem:

SendGrid’s Legacy

• Pioneered scalable email APIs
• Helped define “email as infrastructure”
• Became foundational in developer ecosystems
• Played a key role in popularizing transactional email services globally

Mailjet’s Legacy

• Introduced collaborative email design tools
• Helped democratize email creation for non-technical users
• Strong presence in European SaaS ecosystems
• Promoted unified transactional + marketing email platforms

Conclusion

The historical evolution of SendGrid and Mailjet reflects the broader transformation of email from a basic communication protocol into a sophisticated cloud-based service layer.

SendGrid’s history is defined by developer-first innovation, infrastructure scaling, and enterprise adoption, culminating in its acquisition by Twilio and integration into a global communications platform. Mailjet’s history, meanwhile, is shaped by collaboration, accessibility, and unified email management, ultimately becoming part of Sinch’s communications ecosystem.

Although they share similar endpoints today—both offering transactional email APIs—their historical roots continue to influence their design philosophy and market positioning. SendGrid remains associated with scale and engineering depth, while Mailjet reflects simplicity, collaboration, and usability.

Together, they illustrate how transactional email services evolved from niche infrastructure tools into essential components of modern digital communication.