What is an ESP or Email Service Provider? A Beginner’s Guide

In this post, I’ll explain what an email service provider or ESP is, how it differs from other email-related services, and the role it plays in your business operations. I will also introduce you to some of the most popular ESPs out there.

What is an email service provider?

An email service provider is a platform to send marketing, transactional, and bulk emails. 

An ESP manages every aspect of email sending: from building and segmenting subscriber lists, creating email content, to analyzing campaign results and improving deliverability rates.

Email service provider vs email provider

Email service providers and email providers are often used interchangeably, but they are two different kinds of platforms:

• Email service providers like Mailtrap, Mailchimp, or SendGrid are designed for businesses, developers, and marketers to send high-volume email campaigns: transactional, marketing, and bulk emails.
• Email providers or inbox providers like Gmail, Outlook, and Yahoo are designed for personal use: sending and receiving emails.

Here are the main reasons why these terms are confused:

• Both help manage emails;
• Some platforms offer the functionalities of both types of software;
• Email providers sometimes allow you to send bulk emails or promotional content, but with limitations. For example, Gmail lets you send promotional emails from your inbox, but it limits you to 500 recipients per email for free Gmail accounts and 2,000 recipients per email for G Suite/Google Workspace accounts.

Characteristic	Email service provider	Email provider
Target audience	Businesses and organizations	Individual users or teams, small businesses
Primary use case	Sending, managing, and tracking large-scale email campaigns, transactional, and bulk emails	Sending and receiving personal or business emails
Types of emails	Marketing emailsTransactional emailsBulk emails (not in all platforms)	Personal emailsProfessional communicationOccasional promotional content
Key features	Email deliverability, contact list segmentation, analytics, automation, high-volume sending, A/B testing, security	Inbox management, basic email sending/receiving, spam filters, email hosting
Examples	Mailtrap, Mailchimp, SendGrid, Mailgun, Brevo, Mailjet	Gmail, Yahoo Mail, Outlook, Zoho Mail, ProtonMail, iCloud Mail, AOL Mail

The main difference is that email providers are designed for individual users for regular email communication, such as sending and receiving personal email messages. While they may also allow you to send bulk emails or promotional content in some cases, their primary purpose is email management and hosting. Popular email providers include Gmail, Yahoo, Outlook, and Zoho Mail.

On the other hand, email service providers are designed for businesses and marketers to handle larger-scale email campaigns, such as newsletters, transactional emails, or marketing automation. They focus on features like email deliverability, analytics, email list segmentation, and automation, which regular email providers do not typically provide. Mailtrap, SendGrid, Mailgun, and Amazon SES are examples of popular email service providers.

The role of an email service provider

An email service provider’s main job is to deliver emails. Email deliverability is a complex process that involves email authentication, spam filtering, inbox placement, and more.

ESPs handle these complexities behind the scenes, enabling you or your team to focus on creating engaging content and building relationships with your audience. 

Let’s break down the role of an ESP and the benefits a business gains when sending different types of emails.

It helps you save on communication and promotion costs

ESPs let you send a large volume of marketing emails without significant infrastructure costs. 

For example, Mailtrap delivers 1,000 emails for just $1.65, which is much more affordable than using other channels for lead generation. A Litmus survey proves this. After interviewing over 1,000 marketers, the survey revealed that 41% of marketers consider email as their most effective marketing channel.

Also, businesses can use bulk emails to promote their products and services without the high costs of traditional advertising. By segmenting email lists and targeting the right audience, they can send relevant content that boosts engagement and conversion. 

ESPs simplify the email creation process with pre-built templates, drag-and-drop editors, customizable layouts, and content blocks. These tools allow marketers to quickly design professional-looking emails, saving time and making the process more efficient.

For example, a team might use an ESP to segment customers who abandoned their shopping carts, create an email template with dynamic content, set up an automated email campaign offering a discount on previewed items, and send follow-up reminders to encourage them to complete their purchase.

It helps your product run smoothly with transactional emails

If users don’t receive transactional emails, they can’t complete critical actions on your website, web app, or platform. They won’t be able to sign up, create an account, make a purchase, or track an order. In just a few minutes, the customer is lost for good.

An ESP handles transactional emails, letting your product work smoothly and providing users with all the necessary information.

For developers, the interface often includes API and sometimes SMTP integration options, giving flexibility for how transactional emails are sent. Many ESPs also provide webhooks, so developers can set up real-time triggers and connect email notifications with systems like e-commerce platforms or customer support tools. 

For example, a developer might use the API to connect email notifications to a subscription-based service, sending reminders for upcoming renewals, confirmations for new subscriptions, and transaction receipts. They can also integrate an ESP with a loyalty program to send users reward point updates or personalized offers based on their activity. 

It tracks email performance to help you improve

One of the biggest advantages of ESPs is their detailed reporting and analytics, which allow businesses to track key metrics, such as open rate, click-through rate, and conversion rate, in real-time and over time.

These insights help businesses understand customer behavior, needs, and expectations, optimize campaigns, and refine future marketing strategies.

It ensures compliance and secures your email operations

ESPs provide built-in features, such as an unsubscribe link, two-factor authentication, and secure data storage, to help you maintain high levels of security and comply with regulations like GDPR (EU), CAN-SPAM (US), PDPA (Singapore), APPI (Japan), CASL (Canada), and other mandatory laws.

These features ensure that your emails are sent securely, customer data is protected, and your business adheres to industry standards.

It drives automation and personalization at scale

Imagine getting a recommendation from your favorite bookstore for Harry Potter and the Sorcerer’s Stone. After purchasing it, you receive a follow-up email with a special deal on Harry Potter: The Illustrated Edition—complete with magical quotes and artwork. You end up buying that too—thanks to a perfectly timed, personalized email

ESPs help businesses automate email sequences and personalize content based on user behavior, demographics, purchase history, preferences, and more. With advanced AI-driven segmentation, hyper-personalization, and granular targeting, you can send tailored campaigns at the right time with subject lines—and content—that will resonate with customers. 

It lets you communicate directly with your subscribers

With emails, you have a direct line of communication with your customers several times a week. You can easily track if your emails are opened and see how users engage with them—or if they ignore them altogether. 

Imagine a customer doesn’t respond to your email. You could follow up with a special offer or incentive to get their attention again. Or, you could simply ask them what kind of content they’d like to receive, making it easier to personalize future emails and keep things relevant for them.

Email is the only channel that allows you to communicate with your audience in both directions. It’s cost-effective, and you can easily track what works and what doesn’t.

List of popular email service providers

Let’s take a look at some of the most popular and universal (ones that can be used in any industry) ESPs out there: 

• Mailtrap is a reliable email service provider for marketing, mass, and transactional emails with industry leading analytics.
• SendGrid. A scalable ESP service for high-volume senders who need extended marketing capabilities, like email automation and personalization.
• Brevo (formerly Sendinblue). A versatile ESP that offers an all-in-one platform with email marketing, SMS, and automation tools, perfect for small to medium businesses.
• Mailchimp is a popular ESP with CRM capabilities that is known for its easy-to-use interface. 
• Mailjet is a versatile ESP with advanced automation tools that help businesses create efficient workflows for marketing and transactional emails.

	Free plan limits (emails per month/day)	Pricing (in US $)	Cost per 1K emails*(in US $)	Testing inbox
Mailtrap	1,000 / 200	20	0,40	✅
SendGrid	3,000 / 200	19.95	0.83	✅
Brevo	9,000 / 300	29	1.45	⛔
Mailchimp	1,000 / 500	20	1.88	✅
Mailjet	6,000/200	17	0.74	✅

Besides these, there are many other services that you can use to cover your email needs, such as:

• Amazon SES is a great tool for large-volume senders and companies with irregular sending needs due to its pay-per-sent pricing model. However, it lacks an interface for marketers and is mainly developer-focused.
• Postmark is a solid instrument, known for its high deliverability and speed. However, it only specializes in transactional emails and cannot be used for email marketing campaigns.
• Mailgun. Focused on developers, Mailgun offers clear API documentation that lets developers create custom email workflows and integrate it with other tools and solutions.
• Constant Contact is a great tool for small businesses. It offers an easy-to-use interface, however, it lacks advanced transactional email support and is not ideal for larger, more complex needs.
• Omnisend supports both transactional and marketing emails and offers strong automation features specifically for e-commerce businesses. 
• HubSpot offers a comprehensive CRM with email marketing capabilities. However, it doesn’t specialize in transactional emails, which limits its capabilities for certain use cases.
• Klaviyo can handle marketing and transactional emails, yet, it’s primarily geared toward retail and may not be suitable for non-retail businesses.
• Campaign Monitor is an easy-to-use email marketing platform that doesn’t support transactional emails. It is best known for its intuitive drag-and-drop email builder and strong analytics.

How to choose email service provider

When selecting the right ESP for your business, it’s important to consider several factors to ensure the platform aligns with your demands. Here’s how to approach the process:

Define your business needs

First, consider what you need an ESP for. Do you need to send transactional, marketing, or bulk emails? What do you want to achieve, and can you do it without an ESP?

Explore and compare features

Different ESPs offer varying features. Some may be better suited for transactional emails (e.g., Postmark), while others offer robust marketing automation (e.g., Mailjet). Some focus on basic functionality, while others offer a range of advanced features.

Make a list of necessary functionalities and compare what each platform offers at a reasonable price. Consider checking the following:

• Email deliverability rate
• Reliable infrastructure
• Security and compliance features
• Advanced automation
• Hyper-personalization (dynamic content)
• Advanced email testing
• Integration options
• Responsive customer support, etc.

Research customer feedback

Look for user reviews and testimonials on platforms like G2 and Capterra to find out the strengths and weaknesses other users found. Feedback on customer experience, support, deliverability, and usability can help you gauge the platform’s effectiveness.

Test the platform

Most ESPs offer free trials or free plans. Take advantage of these opportunities and test the platform’s usability, features, and support. Send test campaigns to check how well the platform meets your email needs and whether it integrates smoothly with your other tools.

Consider pricing and scalability

Think about your current and future needs. Ensure the platform you choose offers a flexible pricing structure that fits within your budget. Be mindful of advanced features, as they typically come as part of higher-tier plans.

Looking for the best email service provider?

Depending on your needs, I recommend checking out our comparison articles:

• 6 Email Marketing Platforms Compared – if you’re looking for an email marketing solution.
• 7 Best Free Email Marketing Platforms – if you’re looking for a free solution for your marketing needs.
• 6 B2B Email Marketing Software – if you’re operating in the B2B sector.
• Best Email Marketing Software for Startups – if you’re specifically looking for a tool tailored to startups.
• SMTP Providers Compared – if you need an SMTP solution for both marketing and transactional emails.
• Choosing the Best Transactional Email Service – if you’re focused solely on transactional email platforms.
• Which Mass Email Service Provider Is Right for You  – if you’re looking for a mass email delivery platform.
• Email Deliverability Comparison – if you need a solution with top-tier deliverability rates.
• What’s the Best Email API Service for Developers – if you’re looking for an API-based solution for your email needs.
• 7 Best Email Hosting Providers – if you’re considering email hosting services.

And if you’re in need of a non-US-based provider, we cover the best in this video:

For those of you looking for a reliable and effective email service provider, Mailtrap offers a straightforward solution with great deliverability, powerful email testing, and industry-leading analytics to deliver professional emails and learn from each campaign.

Wrapping up

Now that you know what an email service provider is and how it can support your business, you’re better positioned to choose the right tool for your company. Whether you’re sending marketing or transactional emails, the right ESP will help you grow your email marketing efforts and fully capitalize on its benefits.