What is an Email API? Everything you need to know

Are you building an online business, digital product, application, SaaS, or something similar? Then you’ll probably need an email API—to send transactional emails like password resets or receipts, set up single sign-on, welcome new users, etc.

Whether you are familiar with terms like email API, SMTP, transactional emails, and so on or not, this article will give you an overview of what you need to know and your choices. Dealing with emails and their delivery is not an easy task, but I’ll simplify it for you and guide you through the processes as seamlessly as possible.

What is an Email API?

To start with the basics, an API (short for Application Programming Interface) enables two or more software applications to communicate with each other.

An email API is a type of API that enables interactions between your website or application and the Email Service Provider (ESP).

Email APIs provide a modern, efficient, and secure way to send and/or receive emails while having access to additional functionalities such as:

  • Email analytics
  • Bounce and spam protection
  • Contact list management
  • Creating email templates
  • Email personalization
  • Bulk email sending
  • Scheduled email sending

Example of an Email API:

const configureSidemail = require("sidemail");
const sidemail = configureSidemail({ apiKey: "your-api-key" });
const response = await sidemail.sendEmail({
    toAddress: "user@email.com",
    fromName: "Startup name",
    fromAddress: "your@startup.com",
    templateName: "Single sign-on",
	templateProps: { url: "https://your.app/sso?token=123" }

Email API vs SMTP & which one to choose

So, you might have heard about Email APIs and SMTP and are trying to figure out the right choice for you.

Generally, if you’re building any web service, application, or SaaS, an email API is what you want to go for. It provides an efficient, flexible, and reliable way to send and receive emails.

SMTP (short for Simple Mail Transfer Protocol) is one of the older communication protocols used by mail servers for email sending and receiving. It was widely used before the introduction of email APIs.

Today, SMTP is still used by email service providers in the background for communication between servers. Additionally, SMTP might still be a convenient choice for some users of WordPress or similar CMS, as they can have an email plug-in, making email integration as simple as copying and pasting SMTP credentials. For all other use cases, an email API is the recommended approach for programmatic email sending.

Benefits of Using Email API

As mentioned earlier, Email APIs are today generally the best and most preferred way to send emails. Their benefits include:

  • Efficiency and ease of use – Email APIs streamline the process of sending (or receiving) emails. Integration can be completed within minutes. Note: The duration may vary depending on the Email API service you choose; with Sidemail, for example, integrating transactional emails takes less than 30 minutes.
  • Flexibility – Email APIs provide greater flexibility for sending, receiving, and managing emails and customizing their content.
  • Access to advanced features – With an Email API service, you gain access to advanced features such as email analytics, history, deliverability monitoring, bounce and spam reports, and more.
  • Scalability – Email APIs scale extremely well. So, you don’t have to worry about rapidly growing your user base; email API services will reliably handle your email delivery.

Types of Email APIs

Generally, we recognize two categories of Email APIs:

  • Email Sending API

    As the name suggests, the Email Sending API handles outbound emails. It facilitates sending transactional emails, such as password resets, single sign-on, or receipts, as well as promotional marketing emails and newsletters. You can read more about transactional and marketing emails here.

  • Receive Email API

    On the other hand, the Receive Email API enables the reception of inbound emails.

Additionally, Email APIs can be categorized as:

  • Transactional Email API

    Transactional emails are emails that are sent as a direct response to a user’s actions in an application, service, or website. Transactional email API can be used to send, for example, account activation email, password reset, receipt, single-sign-on, etc.

  • Email Marketing API

    The second category is Marketing Email API. It’s used to send promotional emails (also known as commercial, bulk emails, or broadcasts). You can use it to send, for example, weekly/monthly newsletters, product updates, promo offers, announcements, and similar.

If you have a SaaS or any application, an email-sending API is a crucial part of the service. Therefore, this article primarily focuses on sending emails. In the following sections, we'll delve deeper into API services for email sending.

Sidemail website image
Example of a transactional email (source: Sidemail.io)

Choosing the Best Email API – criteria

The best email API should match your use case as well as technical criteria.

  • Reliability – Deliverability rates and speed are crucial for transactional emails. A good email API service should deliver your emails quickly and reliably; every time and anytime.
  • Good developer experience and smooth integration – Integrating transactional emails should not be a process that takes weeks of developers’ focus. Look for an email API service with well-written documentation, clear instructions, and industry-standard best practices to streamline the integration process.
  • Customer support – When in need, you’ll appreciate having the possibility of reaching customer support who will help you resolve your questions and issues and be there to assist you further.
  • Price & Scalability – The chosen Email API should offer flexible pricing plans that allow you to scale up or down as needed without penalties or waiting for billing cycles.
  • Premade email templates and design – No one wants to deal with broken HTML emails. Coding and testing templates that work well in all inboxes and devices is a daunting task. A good email API service will give you a head start by providing you with templates they have created and tested. All you need to do is select your branding like logo, font, colors, etc.
Sidemail website image
Example of email API documentation (source: Sidemail Docs)

Best Email API Service

Crucial factors in choosing the Email API service are technical characteristics, reliability, easiness of use, price, and scalability. However, your preferences and the specifics of your use case are also important considerations. You can read a detailed comparison of API services for sending transactional emails here.

  1. Sidemail
  2. Sendgrid
  3. Mailgun
  4. Postmark
  5. Amazon SES

Wrapping up

You’ve learned all the essentials about email APIs, now let’s move from theory to action. And if you stumble upon any question, feel free to reach out at kristyna@sidemail.io. I’m happy to help you with your email delivery.

👉 Try Sidemail today

Dealing with emails and choosing the right email API service is not easy. We will help you to simplify it as much as possible. Create your account now and start sending your emails in under 30 minutes.

Start 7 day free trial →

More articles: