10+ Best Email APIs in 2023 for Developers [Free & Paid]

Discover the best email APIs for 2023. Get the top picks from our list of both free and paid options to help you integrate email into your applications quickly and easily.

10 Best Email APIs in 2023

With the right email API, you can easily send and receive emails in your application, allowing you to focus on building critical, differentiating communications features that drive in-app engagement and maximize retention.   

This post will review some of the best email APIs on the market, cover the most important features, and discuss different pricing models and how they work so you can make an informed decision about the right one for you. 

Let’s get started!

What are email APIs?

Email APIs (Application Programming Interfaces for emails) are a set of protocols and tools that allow developers to integrate email functionality into their applications. With an email API, users can send and receive emails, retrieve email messages, manage email addresses, and perform other email-related tasks all within an organization’s platform. 

Other email API capabilities include: 

  • Sending automated emails to users (e.g., welcome emails, password reset emails)
  • Using incoming emails to trigger certain actions (e.g., creating a task in a project management app when an email is received)
  • Retrieving information about emails, such as subject lines and sender addresses
  • Track contact lists
  • Report on key metrics like open rate and clickthrough rate (CTR)

There are several categories of email APIs available, including web APIs, SMTP (Simple Mail Transfer Protocol) APIs, POP (Post Office Protocol) APIs, and IMAP (Internet Message Access Protocol) APIs. 

Each of these protocols has its own set of features and capabilities, and developers can choose the one that best fits their needs. Using an API means developers can connect their apps to email providers in minutes – without any coding required.

SMTP vs. web API

SMTP APIs and web APIs are application programming interfaces that allow different software systems to communicate with each other. 

SMTP APIs allow you to interact with email servers and services programmatically and can be used to send automated emails, receive and parse emails, and manage email lists.

Web APIs enable communication between various applications, services, and systems. They can be used to retrieve data, perform tasks, and interact with other systems in various ways. These APIs are typically implemented using HTTP and JSON and are often used to build integrations between different software systems or to expose data or functionality to developers.

Types of email APIs

Transactional vs. contextual email APIs

Transactional vs. contextual 

Transactional APIs are best for businesses that need to send out a massive volume of emails in quick succession that require very little customization. These types of APIs are best suited for automated marketing updates, promotional offers, and transactional notifications. 

Contextual APIs are best for businesses that need to send and receive emails in a conversational context. These APIs facilitate personalized interactions such as sales outreach, customer service inquiries, or tailored newsletters. Conversational APIs allow users to send messages directly from their own address, customize each message with HTML and images, as well as use analytics tracking to measure engagement rates – all while ensuring high deliverability rates.

Sending vs. receiving

Sending APIs allow you to automate email messages and tailor them according to your business’s needs. Both transactional and contextual APIs support sending capabilities. 

Receiving APIs allow organizations to receive emails from customers or other third parties. You can connect your existing email service with an external provider to receive more emails at once without having to manage each message manually. 

Transactional APIs can offer support for receiving email, but if you’re sending and receiving messages within the context of a conversation, contextual APIs provide a far better end-user experience.

Benefits of using email APIs

Some of the key benefits of using email APIs include:

  1. Email deliverability 

Businesses and organizations can increase the deliverability of their emails by ensuring that they follow best practices for sending emails. This includes obtaining permission from recipients before sending emails, using a reputable and properly configured email server, and following guidelines for spam filtering.

With improved email deliverability, you can send directly from your users’ inboxes and avoid proxy sends.

  1. Personalization 

APIs allow companies to incorporate personalization into email campaigns by allowing them to access and use data about the recipient, such as their name, location, or past interactions with the business. This data can be used to create personalized email subject lines, content, and calls to action tailored to the individual recipient.

  1. Analytics 

An email API can provide a range of analytics and tracking capabilities, such as real-time email tracking, open and click-through rates, and conversion tracking. This helps businesses and organizations assess the effectiveness of their email campaigns.

  1. Seamless integrations 

Email APIs allow developers to integrate email functionality into their applications or websites easily. For example, eCommerce websites can use native email integrations to send confirmation emails or personalized product recommendations to customers, while CRM systems can also use email APIs to send automated outbound cadences and follow-ups.

  1. Cost & time savings

By integrating their existing email service with third-party services, businesses can save money and time by streamlining the process of sending emails from their app. Email APIs abstract away the burden of building email features on your own, saving thousands of developer hours and allowing you to launch new capabilities in weeks or months. 

Plus, these APIs drastically reduce the ongoing maintenance burden, bug resolution, and accounting for unforeseeable customer edge cases that every integration requires. 

In short, APIs let you reinvest your team’s time and energy into delivering differentiating features that drive engagement and boost retention.

Best email APIs

As businesses continue to rely on email for communication and customer service, having an effective way to receive and send emails is essential. This is where the best email APIs come in. 

Let us explore 11 of the best options available on the market and discuss their key features, capabilities, and pricing.

  1. Nylas 

How it works:  Nylas is the best email API in 2023 because it is the fastest and easiest way to connect to your users’ inboxes and stand up engaging email capabilities. The Nylas platform enables businesses to save thousands of developer hours and build powerful email, calendar, and contacts features so you can focus on your customers, not infrastructure.

Additionally, the Nylas Email API provides companies with industry-leading 99.9% deliverability, ensuring your users’ messages land in the inbox, not SPAM. Nylas is also well known for its highly secure, scalable architecture and highly responsive customer support team.

Key features:

  • Universal API that connects to 100% of email service providers 
  • Stand-up bi-directional sync and full Create, Read, Update, Delete (CRUD) capabilities
  • Nylas Express Security Review so you can complete the Google Cloud Application Security Assessment quickly and at a low cost
  • Access to powerful unstructured email data
  • Message tracking and analytics 
  • Dedicated and responsive customer success team


Nylas offers a full-service API platform including an email API, calendar API, and contact API. Pricing plans vary by the number of connected accounts (end users).

To choose the best plan for your business, talk to an expert to get a quote today. 

  1. SMTP.com

How it works: SMTP.com is a transactional API solution that enables IT professionals and developers to integrate email into their web applications. Businesses can tailor their emails according to the recipient’s preferences, such as geographic location, device type, etc. Additionally, users can track their email campaigns in real time with analytics. 


Key features:

  • White-listed IP addresses
  • Email authentication
  • Monitoring systems
  • ISP feedback loops
  • Shared IP addresses


SMTP offers four pricing levels: 

  • Essential: $25/month
  • Starter: $80/month
  • Growth: $300/month
  • Enterprise: $500/month
  1. SendGrid

How it works: Sendgrid provides users with a transactional email API for managing their emails, enabling businesses to reach a wider audience reach. Sendgrid’s analytics allows users to monitor email campaigns and measure their success. The platform also offers tracking features, such as open rates, click-through rates, and more. 


Key features: 

  • Email segmentation 
  • Mail send API
  • Tracking and reporting 
  • Domain reputation 
  • Enterprise scalability 


Sendgrid offers three pricing levels:

  • ESSENTIALS (40K, 100K Packages): $14.95 to $29.95/month
  • PRO (100K, 300K, 700K, 1.5M, 2.5M Packages): $89.95 to $949.95/month
  • Premier Plan: Contact SendGrid for a quote
  1. Amazon SES

How it works: Amazon SES is a transactional email service provider that can integrate into email-sending applications. Amazon SES offers analytics to measure deliverability rates, open rates, click-through rates, and more. Amazon SES includes security features against attackers and phishing scams


Key features: 

  • Sender configuration options
  • Inbox deliverability
  • Deployment options
  • Inbox simulator
  • Email receiving


Amazon SES offers four pricing levels:

  • Email Messages: $0.10 per 1,000 email
  • Data Transfer: $0.00
  • Attachments: $0.12 per GB of attachments sent
  • Mail Chunks: $0.09 per 1,000 mail chunks
  1. Mailgun

How it works: Mailgun is a cloud-based email service that allows users to send and track transactional emails. The platform enables businesses to customize emails according to the recipient’s preferences, such as language or device type. 

Mailgun’s analytics dashboard provides information about the performance of emails, including open rates, click-through rates, and more. Users can also use Mailgun’s drag-and-drop editor to create HTML emails. 


Key features: 

  • Email tracking and analytics
  • Inbound email routing
  • Spam filter testing
  • Send time optimization
  • Suppression management


Mailgun has five pricing editions:

  • Flex Trial: Free trial/month
  • Foundation: Starting at $35/month
  • Growth: Starting at $80/month
  • Scale: Starting at $90/month
  • Enterprise: Contact Mailgun for a custom quote
  1. Sendinblue 

How it works: Sendinblue is an email marketing service that comes with a drag-and-drop editor for creating professional emails and analytics for tracking the performance of campaigns. The Sendinblue Email API lets developers send millions of transactional emails directly from an application. 


Key features: 

  • Deal pipeline management
  • Live chat and chatbot
  • Marketing automation tools 
  • API integrations
  • WhatsApp campaigns


Sendinblue offers four pricing plans: 

  • Free: $0/month
  • Lite: $25/month
  • Premium: $65/month
  • Enterprise: Get a custom quote from Sendinblue
  1. Postmark 

How it works: Postmark is an email delivery service designed to allow developers to send marketing and transactional email with high deliverability.

Postmark also provides users with various API-based tools for monitoring deliverability and preventing bounces. In addition, the platform provides businesses with templates for password resets, welcome emails, receipts, invoices, user invitations, and more.

Key features: 

  • Spam Blocker
  • Email Monitoring
  • Data Recovery
  • Response Management
  • Signature Management


Postmark offers eight pricing levels:

  • 10,000 emails: $10/month
  • 50,000 emails: $50/month
  • 125,000 emails: $100/month
  • 300,000 emails: $200/month
  • 700,000 emails: $400/month
  • 1.5M emails: $700/month
  • 3M emails: $900/month
  • 5M emails: $1,200/month
  1. SparkPost

How it works: Sparkpost is an email delivery platform that helps businesses predict and monitor ISP responses, email bounce rates, and spam traps in real time. The inbox tracker enables marketers to create and send emails using subject line prediction, blacklist monitoring, and brand impersonation protection methods.

Additionally, users can configure two-factor authentication and SSL encryption to provide a secure user experience. SparkPost also comes with an API that allows businesses to integrate the system with other third-party solutions.

Key features: 

  • Single email verification
  • Spam detection
  • Syntax check
  • Real-time alerts
  • Webhooks integration 


Sparkpost has four pricing models: 

  • Starter: $20/month
  • Premier 100K messages: $75/month
  • Premier 250K messages: $170/month
  • Premier 1M messages: $525/month
  1. Mailchimp

How it works: Mailchimp is a web-based marketing automation service that allows users to share newsletters on social networks and track customer engagements. Mailchimp offers a marketing API, transactional emails, and an API-first commerce stack. Organizations can manage audiences, integrate data, and send timely email campaigns.

Key features: 

  • Automated Scheduling
  • Email Tracking
  • Collaboration Tools
  • Social Marketing
  • Click Tracking


Mailchimp offers four pricing levels: 

  • Free: $0
  • Essentials: $13/month
  • Standard: $20/month
  • Premium: $350/month
  1. Mailmodo

How it works: Mailmodo is an API that helps companies design, test, and deliver emails on different devices and browsers. It provides a platform to create professional email campaigns from scratch or existing templates. 

Mailmodo is a no-code ESP solution that has all the features of a traditional ESP, like email analytics, sending transactional campaigns, email automation and drip emails with customer journeys, drag-and-drop email editor, useful integrations with CRMs, connectors, marketing tools, and more.


Key features: 

  • List Management
  • Reporting/Analytics
  • Deliverability and open rates
  • No-code emails
  • Audience segmentation


  • Free Trial
  • Silver: $99/month
  • Gold: $249/month
  • Platinum: $599/month

More top email APIs

Looking for a specific email API? Here are some of the best email API options for sending, receiving, and more. 

Best Email API for Google integration

  • Nylas
  • SendGrid 
  • Postmark 

Best Email API service for developers

  • Nylas
  • SMTP.com
  • Email Engine

Best free email API 

The following APIs offer free plans: 

  • Mailgun 
  • Sendinblue  
  • Mailchimp 

Best REST Email API to send emails 

  • Nylas 
  • Mailchimp
  • Amazon SES

Best receiving email API 

  • Nylas
  • Mailmodo
  • SparkPost

Nylas allows organizations to sync, send, and receive emails, while many other options only provide sending capabilities. 

Choose the best email API

There are many excellent email APIs on the market that can help businesses and organizations to improve their email communications and marketing efforts. 

With its universal connectivity, bi-directional sync, and unparalleled reliability, Nylas is a top choice for businesses and developers looking to stand up engaging, embedded email capabilities in their applications. 

Whether you need to send automated emails, track real-time performance, or personalize your messaging, Nylas has the tools and capabilities you need to succeed. 

Start your trial today, and enjoy a stress-free emailing journey with Nylas.

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