For developers building web and mobile apps, delivering fast, reliable, and affordable transactional email is non-negotiable. Whether it’s password resets, order confirmations, or alert notifications, these one-to-one emails keep users informed and engaged in real-time. While services like Mailjet and SendGrid are often the go-to providers, they’re not the only options — and in many cases, not even the most cost-effective.
TL;DR
Looking for a robust, cost-effective alternative to Mailjet or SendGrid? There’s a host of excellent transactional email APIs out there that provide scalable, developer-friendly platforms for sending email alerts. Postmark, Mailgun, and Amazon SES are just a few names that combine reliability with affordability. This article breaks down seven top choices and what makes them stand out, so you can find the best fit for your project.
What Is a Transactional Email API?
A transactional email API is a service that allows you to programmatically send one-to-one emails based on user actions or system events. These APIs are crucial for time-sensitive notifications such as:
- Account creation confirmations
- Password resets
- Purchase receipts
- Shipping updates
- Security and login alerts
Unlike marketing emails, transactional emails must arrive instantly and reliably — your users expect nothing less.
The 7 Best Transactional Email APIs & Sending Services
We’ve curated this list based on criteria such as price, deliverability, API ease-of-use, documentation quality, and developer support. If you’re looking for Mailjet or SendGrid alternatives, here are the top options:
1. Postmark
Why developers love it: Blazing fast delivery speeds and industry-leading reliability.
Postmark is famous for delivering transactional emails in a fraction of a second and actively avoids marketing content to preserve a clean IP reputation. Their API is clean and simple, with packages for popular frameworks and languages like Ruby, Node.js, Python, and PHP.
- Free Tier: No free tier
- Pricing: Starts at $15/month for 10,000 emails
- Strengths: Speed, deliverability, detailed message tracking
2. Mailgun
The developer’s choice since the early days, Mailgun has excellent documentation, strong APIs, and a focus on flexibility. It also offers advanced features like email validation and analytics, which make troubleshooting a breeze.
- Free Tier: Up to 5,000 emails in the first month
- Pricing: Pay-as-you-go or tiered plans
- Strengths: Programmable, scalable, suitable for high-volume use
While Mailgun’s deliverability can vary depending on your plan (shared vs. dedicated IP), the platform remains a favorite among technical teams for its integrations and control.
3. Amazon SES (Simple Email Service)
If you’re already on AWS or building large-scale systems, Amazon SES is worth serious consideration. It’s a no-frills, super-affordable email sending service with high scalability and solid integration into the AWS ecosystem.
- Free Tier: 62,000 emails/month (when sent from an EC2 instance)
- Pricing: $0.10 per 1,000 emails sent
- Strengths: Extremely cheap, scalable, great for large workloads
However, SES lacks some polish and ease of setup compared to competitors, so it’s better suited to developers who are comfortable with AWS services and infrastructure.
4. SMTP2GO
SMTP2GO offers both SMTP and web API support, great deliverability rates, and friendly customer service. It’s ideal for small to medium-sized apps looking for a plug-and-play alternative that doesn’t break the bank.
- Free Tier: 1,000 emails/month
- Pricing: Starts at $10/month for up to 10,000 emails
- Strengths: Easy to configure, good reporting, global servers
What’s more, SMTP2GO provides a beautiful dashboard with real-time logs and message status — a feature often missing in ultra-budget options.
5. Pepipost (now part of Netcore Cloud)
Pepipost combines affordability with a great reputation in deliverability. Their emails are powered by a machine-learning engine designed to optimize inbox placement.
- Free Tier: Up to 100 emails/day forever
- Pricing: Competitive pay-as-you-use pricing
- Strengths: AI-enhanced deliverability, great dashboard
What makes it developer-friendly is their RESTful API and support for real-time event notifications like bounces, opens, and unsubscribes.
6. Resend
One of the newer players in this space, Resend is focused solely on transactional email and built to be extremely simple for developers to use — especially those working with modern frameworks like Next.js and Vercel.
- Free Tier: 3,000 emails/month
- Pricing: $20/month for up to 50,000 emails
- Strengths: Clean API, fast onboarding, minimal setup
Resend is built by developers, for developers — with an emphasis on using email as a component in your modern web apps. If you’re looking for simplicity and integration with your dev stack, it’s an excellent choice.
7. Elastic Email
Last but not least, Elastic Email is known for being incredibly affordable and rich in features. Whether you use SMTP or their HTTP API, Elastic offers tools for both transactional and promotional emails (though you’ll want to separate IPs).
- Free Tier: 100 emails/day
- Pricing: From $0.09 per 1,000 emails sent
- Strengths: Price, simplicity, drag-and-drop editor if needed
Its affordability makes it a good fit for startups or bootstrap teams who still want solid analytics and template management.
How to Choose the Right Email API for You
Picking the right transactional email service depends on your needs and priorities. Here’s a quick comparison based on common criteria:
- Best for affordability: Amazon SES, Elastic Email
- Best for ultra-fast delivery: Postmark
- Best for dev-centric platforms: Resend, Mailgun
- Best for all-in-one use (marketing + transactional): SMTP2GO, Pepipost
Developer Tips: What to Look For
When you’re evaluating an email service, keep these developer-specific factors in mind:
- API Documentation: Clear, versioned, well-documented REST interfaces
- SDKs: Available for your preferred programming language
- Logs & Dashboards: Easy to view message events and bounce logs
- Support: Responsive and accessible technical help when things go wrong
- Template Handling: Ability to build, store, and manage templates programmatically
Conclusion
Transactional emails might not have the flair of marketing campaigns, but they are mission-critical to digital experiences. From login alerts to payment confirmations, users demand quick, dependable communication. Fortunately, you don’t have to settle for expensive or bloated solutions.
Services like Postmark, Mailgun, and Resend offer slick developer experiences, while Amazon SES and Elastic Email come through on cost-saving. Understanding your priorities — be it message speed, delivery rates, or deep integrations — will help point you toward the perfect service. With so many Mailjet and SendGrid alternatives out there, better performance and lower costs are just a few clicks away.