What is an Email Service Provider (ESP)?

Email Service Provider (ESP)
Vitalii Poddubnyi Vitalii Poddubnyi 31 may 2022, 15:53 602
For beginners

Email service providers (ESP) help companies and organizations to create and send bulk emails easily without violating email policies while keeping the company’s email servers and domains from getting into blacklists. Many ESPs provide self-service email software to help you create and send transactional emails, newsletters, and promotions in bulk without professional assistance. This type of software can be free or premium.

Based on the services different ESPs specialize in, it is possible to distinguish a number of categories:

  • SMTP relay provider: SMTP Relay is basically an SMTP server for rent, but with some added value. For bulk emails or mass mailings, SMTP relay services can exclude spam by means of authentication, licensing, and their own network. Email servers do not consider emails originating from such a server as spam.
  • Dedicated email service provider: Similar to dedicated SMTPs, dedicated email service providers use their own infrastructure. The advantage of such service is that dedicated systems have a high sender reputation and can be effective in the fight against spam. Dedicated systems often provide additional features such as managing records or delivering emails to a variety of server systems.
  • Web-based and cloud services: Cloud services in the area of email marketing provide their web-based resources to send bulk emails. Usually a web interface is included. Such services are usually implemented as SAAS (Software As A Service). This means that the use of cloud email services is associated with relatively little effort and high level of planning.
  • Integrated marketing platform: Integrated solutions that enable marketing, web analysis, and offer various other sophisticated features. Such solutions are often designed for use in large companies.

Why Use an Email Service Provider?

Key features of good email service providers

An ESP that allows for consistent direct communication with subscribers can be a good, low-cost investment for your business. Also it usually allows you to email customers, prospects, and website visitors automatically. This type of communication attracts website traffic and promotes brand loyalty. The main benefits of ISPs, as compared to simple in-house solutions, are:

  • Email delivery: Using ESP safeguards your deliverability and prevents your domain from getting blacklisted. In contrast, if you are sending bulk emails from your email client, your activity might be flagged as suspicious, and you'll be labeled a spammer.
  • Email compliance regulation: CAN-SPAM act (or similar non-US regulations) governs all email marketing, and most ESPs comply with their requirements. For example, they ensure that you obtain your subscribers' permission before sending out email campaigns.

They also mandate including your company's contact information and an unsubscribe option for subscribers in every email. Therefore, ESPs simplify compliance with email and privacy regulations.

  • List management: ESP automatically keeps your subscribers' list up to date. It automatically adds subscribers who sign up through a subscribe form to your list. In addition, if a subscriber clicks the "unsubscribe" link, the ESP immediately removes them from your list.

Most ESPs allow you to sort and segment your lists by subscription source, subscriber characteristics or activity like opens, clicks, or purchases. They also handle "bounced emails," i. e., emails not delivered due to addresses being inactive or invalid.

  • Flexible templates: Effective emails should have a clean, modern, and visually appealing design and be compatible with mobile devices. Most ESPs offer built-in professional templates that are easily customizable in a few clicks using their drag-and-drop functionality.
  • Marketing funnels and automated email campaigns: An email marketing funnel refers to a series of email messages guiding website visitors through a task to become subscribers and potential clients. Your ESP can also schedule emails for a specific date and time by configuring it to send emails using the data collected from previous interactions.

Examples of Email Service Providers

Examples of email service providers

There are literally dozens of ESPs, each with its own unique benefits. We’ve highlighted just a few of them.

  • UniOne

Unione offers incredible speed, excellent deliverability, quality assistance, and easy setup. In just minutes, you'll be up and running with a Web API or SMTP connection. The service offers GDPR-compliant security and privacy. There's no need to upload any sensitive information; UniOne's servers do not store any personal data (except, of course, the very letter for the duration of mailing, and the target email address for a limited time, to calculate delivery statistics).

  • Sendinblue

Sendinblue is an email service provider that quickly became one of the most popular options for SMBs. This program helps you create and send out email campaigns. It includes features you'd expect from an ESP, such as preset email templates,

automation, A/B testing, analytics dashboard, and more. Sendinblue has also expanded its features beyond email marketing to include full-fledged SMS campaigns.

  • Twilio SendGrid Email API

SendGrid is a trusted platform for transactional and marketing email, offering great deliverability for large volumes. Its deliverability features like domain authentication, proactive ISP outreach help businesses improve open rates.

  • Netcore Email API (formerly Pepipost)

Netcore Email API is a transactional email delivery service that helps businesses send important notifications, newsletters, and updates via its cloud-based infrastructure. Their email API is popular because it focuses on the most important aspects of email marketing: deliverability, pricing, and analytics. Netcore Email API is a good email delivery partner for both startups and industry heavyweights due to its simple integration and disruptive pricing model.

  • Mailgun

Mailgun is an email service provider that specializes in sending, inbound routing, analytics, and validation. They’re heavily API-driven and stand out with quick and easy implementation while providing managed service capabilities.

Which Email Service Provider Is Best?

With so many services to choose from, it’s virtually impossible to name one which would be the best for your particular application. Each service offers its unique benefits, while each customer’s application has its own challenges and requirements. Luckily, you do not have to settle for one ESP once and forever. Try out a few different services to find the best fitting one for your needs. For small volumes and testing, most ESPs offer a free plan. You can even use several different providers at a time, to perform direct comparison of speed and deliverability.


Your ESP's quality, features, and functionality determine your email deliverability and help you decide which email marketing strategies to implement. Some have more features than others, but most advanced tools can be challenging to learn; therefore, using a less complex tool may also be an option.

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