6 Best Email API Services For Developers Tested & Compared: Here’s What I Found

Ivan Djuric

1 month ago

Considering the size of the industry nowadays, I have to say that looking for the best email API (application programming interface) is like searching for a needle in a haystack.

So, I’ve spent the past few weeks going through the haystack of email APIs, then I reviewed the best of them and compiled a nice little list to help you choose the best one for your needs.

Before we dive in, if you feel like freshening up or fine-tuning your knowledge, you can check out the article our email infrastructure expert, Dzenana, has written on email APIs.

Best email API: a snapshot

Click on a platform name to jump ahead to the detailed review.

Mailtrap is best for high-volume product companies that are looking for high deliverability rates, in-depth analytics, and growth-focused features.
Mailgun is best for developer teams who need detailed logs and an email validation API on top of an email API.
SendGrid is best for enterprise users who need granular control over their user permissions.
Amazon SES is best for current AWS users who have extensive experience with delivering emails.
Postmark is best for teams looking to send transactional emails and don’t need any extra features.
Resend is best for developer teams who are using JS stack and need to create dynamic email templates.

I’ve made a chart to help you compare the APIs you might be leaning towards. Check it out.

Email API	Free plan	Pricing	Integration
Mailtrap	3,500 per month	From $15	Node.js, PHP, Ruby, Python, Elixir, Java
Mailgun	100 per day	From $15	Python, Go, Node.js, PHP, Java, Ruby
SendGrid	100 per day	From $19.95	C#, Go, Java, Node.js, PHP, Python, Ruby
Amazon SES	3,000 per month (during the first year)	$0.10 per 1,000 emails	Java, .NET, PHP, Python, Ruby, Go
Postmark	N/A	From $15	Ruby, RoR, .NET, Java, PHP, Node.js
Resend	3,000 per month	From $20	Node.js, PHP, Laravel, Python, Ruby, Go, Java, Rust, .NET

Disclaimer: The ratings, features, and prices are up-to-date as of writing this article, but they could be different when you’re reading it, as they’re prone to change.

Email API providers comparison methodology

To bring you an unbiased, accurate, and comprehensive review of the best email API providers, I conducted a thorough research and tested (almost) everything they offer.

However, I must note that I didn’t conduct the research alone, since I had the help of Mailtrap deliverability experts, security team, and developers who work on our infrastructure.

Documentation research

First and foremost, I made sure to dig through each provider’s:

Official API docs to see how easy to integrate for your team an API is and what it offers (e.g., sending endpoints, bounce handling, templates, etc.).
GitHub repositories to check whether an API is being regularly maintained and updated.
Testimonials and reviews to see what a provider’s user base thinks and how the APIs hold up compared to advertisements.
Knowledge bases and blogs to look for helpful guides and tutorials on setting up and using an API.

Hands-on testing

Recently, over at Mailtrap, we conducted a thorough email API flexibility research where we:

Sent emails with different sending configurations to test real-world use cases such as sending attachments and bulk emails, etc.
Triggered API rate limits and retry behavior to inspect how an API handles high volume, throttling, and retries.
Created email templates to evaluate how much personalization each API allows and to test templating logic and dynamic content.
Set up webhooks for some of the events they support to see how quickly you get automated notifications about the most important metrics like bounces.

Now, let’s get on with the reviews of each email API provider or check out the detailed criteria first by clicking on this jump link.

Best email API: Mailtrap

G2: 4.8 🌟 Capterra: 4.8 🌟

Mailtrap Email Delivery Platform is designed for SaaS teams or product companies with high sending volumes that need high deliverability rates, in-depth analytics, and growth-focused features.

Additionally, Mailtrap offers one of the most flexible email APIs out there that allows developer teams to fine-tune their sending configuration according to their specific needs. Of course, I would never claim this without being able to back it up.

Recently, we’ve performed numerous tests with the top APIs in the industry, simulating real-world usage to see how much control the user gets. Here’s a table that summarizes key findings of our research:

Dedicated IPs	Available from 100k emails/month with auto warm-up.
Separate streams	✅ Bulk and transactional
Rate handling	✅ No limits, customizable throttling
Webhooks	✅ Full events + logs
Templates	✅ Handlebars
Customer support	Ticket, chat, priority support

To learn more about our methodology and get more in-depth information on technical tidbits like IP infrastructure, throttling, retry mechanisms, etc., read our full comparison.

Why is it the best email API?

High deliverability

Mailtrap uses separate sending streams, dedicated IP addresses, email warm-up, throttling, and other advanced features to help all of its users achieve high deliverability rates, regardless of the plan.

The platform also has a team of deliverability experts at its users’ disposal, who can help you with any deliverability-related issues you might face.

Moreover, we’ve recently performed several deliverability tests with top API providers. To make sure the tests were fair to everyone, we used free plans, didn’t warm up domains, used the same template, etc.

Here’s how Mailtrap performed:

Platform	Email placement results	Spam filter rating	Inbox email delivery with top providers
Mailtrap	Inbox: 78.8% Tabs: 4.8% Spam: 14.4% Missing: 2.0%	Google Spam Filter: Not spam; Not phishy Barracuda: Score 0 Spam Assassin: Score: -3.8	Gmail: 67.50% Outlook: 77.78% Hotmail: 100% Yahoo: 55.56%

Source

In-depth analytics

With Mailtrap, you can keep an eye on the performance of your email campaigns thanks to helicopter view dashboards and drill-down reports. These let you track email metrics like opens, clicks, bounces, and others.

Additionally, Mailtrap will keep your email logs for up to 30 days,

Email templates

Besides the drag-and-drop email builder, which can make your marketers’ lives easier, Mailtrap offers an HTML editor your devs can use to create email templates from scratch.

The templates use the Handlebars engine with which you can set up additional variables and conditional variables like if and else statements to automate a big portion of your sending workflow.

Pricing

Mailtrap offers several different scalable plans and has one of the most cost-effective email APIs since it doesn’t keep customer support or high inboxing rates locked away for higher tiers.

As of writing this article, the most popular plan is Business 100k, being in the golden middle and offering a plethora of advanced features with 100,000 monthly emails at an affordable rate.

Here’s a quick table that sums the pricing plans up:

Plan	Monthly cost	Email limit	Key features
Free	$0	Up to 3,500 emails	SMTP relay, SMTP API, drag-and-drop editor, webhooks
Basic	From $15	10,000+ emails	Email logs (5 days), body retention, click-rate tracking, HTTPS link branding
Business (the most popular)	From $85	100,000+ emails	Email logs (15 days), dedicated IP, auto warm-up
Enterprise	From $750	1,500,000 emails	All of the above + priority support and 30 days email log retention
Custom	Custom	From 1,500,000	All of the above

For more details, please consult the official Mailtrap pricing page.

Pros

High deliverability rates
Separate sending stream
Industry-best analytics
Advanced webhooks
GDPR compliant
ISO/IEC 27001:2022 certified
24/7 expert support
Free email deliverability consultation
Extensive API documentation
Email marketing suite
Integration to MCP servers via Claude, Cursor, or VSC code editor.

Cons

Currently, you can only integrate Mailtrap with services such as Zapier and Tabular email, but more integrations are on the way.
Automations are still in alpha but the official release is planned for the near future.

Developer experience

Official API documentation

Mailtrap offers easy-to-use SDKs for Node.js, PHP, Ruby, Python, Elixir, and Java.

It offers code snippets for major programming languages, which lets you start sending emails right away. All you need to do is copy/paste the provided script into your sending configuration, insert your credentials, and you’re off.

Here’s a Node.js code snippet offered by Mailtrap:

const Nodemailer = require("nodemailer");
const { MailtrapTransport } = require("mailtrap");

const TOKEN = "<YOUR_API_TOKEN>";

const transport = Nodemailer.createTransport(
  MailtrapTransport({
    token: TOKEN,
  })
);

const sender = {
  address: "hello@demoatmailtrap.com",
  name: "Mailtrap Email",
};
const recipients = [
  "demo@mailtrap.io",
];

transport
  .sendMail({
    from: sender,
    to: recipients,
    subject: "You are awesome!",
    text: "Congrats for sending an email with Mailtrap!",
    category: "Integration",
  })
  .then(console.log, console.error);

The documentation is also quite extensive, regularly updated, and has everything you need in one place.

Additionally, Mailtrap has a blog with step-by-step articles on setting up the platform’s SMTP/API and sandbox with all major programming languages and web dev frameworks, such as:

On top of that, their YouTube team has been busy and provided a lot of follow-along videos on setting up sending functionality, validation mechanisms, and more. Check it out.

Security

From email authentication to detailed logs and monthly DKIM key rotation, Mailtrap has every security element covered:

Encryption & transmission security	Strong TLS enforcement, MTA-STS support
Authentication & identity control	SPF, DKIM, DMARC alignment
API & credentials security	Granular API keys, IP whitelisting
Account access & user controls	MFA, RBAC, detailed audit logs
Abuse prevention & misuse protection	Robust reputation management, real-time security monitoring
Security event logging & notifications	Detailed logs, customizable alerts

Compliance

Mailtrap is compliant with all modern regulations, it’s ISO certified, and SOC 2 certification is in progress:

GDPR	✅ Compliant
Data residency	Based in EU but the servers are in the US
SOC 2, ISO 27001, HIPAA	✅
User rights support	DSAR support & data deletion upon request
Logging	Detailed logs, exportable
DPA	✅ Available on request

Testimonials

While scouring online reviews, I’ve noticed that Mailtrap is praised for its deliverability and dev-friendly API. One of the reviewers also mentioned how the Mailtrap support team helped them resolve DKIM alignment issues within a few hours:

Others like its API for its reliability and rapid delivery time:

Send Emails with Mailtrap

Best for devs: Mailgun

G2: 4.2 🌟 Capterra: 4.3 🌟

Mailgun is a transactional email service that provides an SMTP and email API designed for developers.

Here’s a quick breakdown of its most important features:

Dedicated IPs	Available from 50k emails/month as an add-on and included from 100k emails/month.
Separate streams	❌
Rate handling	✅ Yes, limit not specified
Webhooks	✅ Full events
Templates	✅ Handlebars + versioning
Customer support	Ticket, chat, and phone

Why is it the best for devs?

Webhook API

Mailgun’s webhook API can be supported at the domain level, which can be handy if you’re using multiple domains. Additionally, it supports many engagement events, such as accepted, delivered, spam complaints, and more.

If a webhook delivery fails, Mailgun will retry the delivery for up to 8 hours.

Email validation API

If you want to add email validation logic to your web forms, you can do so with Mailgun’s email validation API. Besides the basic syntax and DNS checks, Mailgun cross-references your email list against its database of 450 billion emails, and warns you about high-risk addresses.

You can also validate your contacts in bulk if you don’t feel like integrating.

Detailed email logs

Mailgun keeps your email logs for up to 30 days, but that’s not their biggest selling point. Namely, what makes them great is the fact that there are 10 filter fields you can use to customize your logs and then analyze them across all your domains.

These include TO and FROM headers, event types, list names, tag names, and others.