What Is an Email Service Provider (ESP) and How To Choose A Good One

What Is an Email Service Provider (ESP) and How To Choose A Good One
18 December, 2023 • ... • 151 views
Sara Kurczyńska
by Sara Kurczyńska

A trustworthy email service provider (ESP) is important for large-scale email marketing operations. Without one, you might find it harder to stay in contact with clients and execute marketing strategies.

But what is an email service provider? What are its key functions and features? And how do you choose the best one out of the bunch? In this article, we will dive into the intricacies of email service providers and help you make the best possible choice.

What is an email service provider (ESP)

An email service provider is a software platform that enables you to send email messages to a large number of email addresses at once. As a result, it’s perfect for running large-scale email marketing campaigns. 

Beyond the basic functionality of sending emails, a good ESP offers a suite of tools designed to enhance and streamline various communication strategies. These include features like advanced email automation, which allows for sending targeted, personalized messages at scale. They are commonly used by email marketing agencies, non-profit organizations, and large e-commerce stores, to name a few.

Types of email service providers

Email service providers can be categorized into different types based on their features, usage, technical details and target audience. The division into types helps users to choose a provider that best fits their specific needs. After all, small businesses have different goals and ambitions from e-commerce giants.

SMTP relay providers

SMTP stands for Simple Mail Transfer Protocol — the standard protocol for sending emails across the internet. An SMTP relay provider offers services that allow users and organizations to send out large volumes of email through their SMTP servers. 

This is especially useful for large-scale marketing campaigns, as well as e-commerce businesses that need to send transactional messages like order confirmations or shipping notices to thousands of recipients. It ensures that these emails are delivered efficiently. It also helps in managing issues like email authentication and reputation. This, in turn, prevents emails from being marked as spam.

Dedicated email service providers

A dedicated email service provider offers specialized email services, typically on a subscription basis. They provide tools for creating, sending, and managing emails, especially for marketing communication at mid-sized agencies or large corporations.

This type of service is scalable, meaning it can cater to both small businesses and large agencies. Features often include drag-and-drop email builders, customizable templates for transactional messages, and campaigns list segmentation. Other notable features are detailed analytics and integrations with things like customer relationship management systems.

Integrated marketing platforms

An integrated marketing platform offers a suite of tools that go beyond allowing you to send out transactional messages in bulk. It typically includes email marketing, but also incorporates other marketing platforms like social media, push notifications, and more. This approach allows for a more holistic view of marketing efforts. It also gives you an easy way to contact and interact with potential and existing customers.

Such platforms often come with advanced features like customer relationship management integration, advanced segmentation, and comprehensive analytics. They are ideal for businesses looking to coordinate and streamline their marketing efforts across multiple channels.

Benefits of using an email service provider

There are several benefits of using an email service provider instead of an email client like Gmail or Microsoft Outlook. The most important ones out of the bunch include improved deliverability and security, as well as scalability and cost efficiency.


Deliverability is a key benefit of using email service providers. They can help businesses monitor their sender reputation. It’s a metric that, if low enough, can get messages classified as spam. By monitoring it, they help businesses achieve higher open rates, ensuring that their sales generation efforts are both efficient and effective. 

On the flip side, email clients lack such a functionality. So, if you choose to use one for large-scale email marketing campaigns, you are likely to end up dealing with decreased sender reputation. This, in turn, will cause your deliverability to tank.


Engagement is another significant benefit. An ESP provides software and features that enable businesses to create more engaging and personalized email content. These tools include mailing list segmentation, for example. It’s what allows you to divide your mailing list into segments based on specific features, such as age, gender, or date of birth. 

Another tool that’s worth mentioning is analytics, which can help in understanding subscriber behaviors and preferences. By utilizing these insights, businesses can tailor their content to resonate more effectively with their audience. This leads to increased sales, open rates, and click-through rates.


Email service providers offer security features to protect sensitive email data, from contact details to the contents of individual messages. This includes data encryption, secure data storage, and compliance with various data protection regulations. This heightened level of security is vital for businesses to protect their reputation and maintain the trust of their customers. It’s also important for staying compliant with email regulations like CAN-SPAM and GDPR.


Scalability is a crucial advantage of email service providers, especially for growing businesses. An ESP can handle large volumes of emails without compromising on performance or deliverability. This means businesses can scale up their email marketing efforts as they grow without needing to invest in additional infrastructure or email marketing resources, such as email marketing software.

Cost efficiency

Finally, cost efficiency is a significant benefit of using an ESP. By outsourcing email infrastructure and management to an ESP, businesses can save on the costs associated with setting up and maintaining their own email servers and systems. On top of that, email service providers offer a range of pricing plans to suit different business sizes and needs. They are often based on the volume of emails sent or the number of subscribers. This flexibility allows businesses to choose a plan that best fits their budget and needs.

Factors to consider when choosing an email service provider

There are several important factors to consider when choosing an email service provider. Paying attention to these factors will help ensure that an ESP aligns well with your business needs, goals, and strategies. 


Usability is a crucial aspect to consider. An ESP should offer an intuitive, user-friendly interface that makes it easy for your team to create, send, and manage email campaigns. In addition, a good ESP will provide drag-and-drop editors for landing pages, customizable templates, and a dedicated template builder, as well as personalization capabilities and straightforward navigation. It enables users to execute their email strategies efficiently, regardless of their technical expertise. 

Additionally, the ESP, just like other email marketing tools, should offer detailed analytics and reporting tools that give you a clear . That way, you will be able to track the performance of your campaigns easily and make data-driven decisions. 

Usability extends to integration capabilities as well. An ESP should seamlessly integrate with other tools and systems you use, such as customer relationship management software or sales generation platforms, to streamline your email and marketing workflows.


The ESP should offer high uptime guarantees and be consistently available. It ensures that you can send email marketing messages without interruptions. 

In addition, a reliable ESP employs best practices for managing contact lists, authenticating emails, and maintaining a good sender reputation. 

The provider should also offer strong customer support services, including timely technical assistance and resources. These resources should include things like user forums and tutorials on email subject lines and personalization.


Security is paramount, especially when handling sensitive customer data and complying with data protection regulations like GDPR. So, the ESP should offer free security features, such as secure data transmission, encrypted storage, and regular security audits. They should have clear policies and measures in place to protect against data breaches, unauthorized access, and other cyber threats. 

Additionally, the provider should be transparent about their data handling practices and comply with international data protection standards. This ensures that your customer data is safe and that your email marketing practices adhere to legal requirements.


The range of features offered by an ESP is a critical consideration. Look for features that align with your email marketing goals, such as advanced segmentation and marketing automation. The ability to segment your audience and take advantage of email marketing automation lead capture tools allows you to send email campaigns that are more targeted and effective.

The ESP should also offer comprehensive analytics and reporting tools to track key performance indicators like open rates, click-through rates, and conversion rates. These tools provide insights to continually refine your email strategy.


Finally, the pricing structure of the ESP should be transparent and scalable to suit your business size and email volume needs. 

With that in mind, compare the pricing plans of different providers. Consider the upfront costs, as well as any additional fees for extra features. Then, go with a cost-effective or even free ESP that will both enable you to maximize your email marketing efforts and fit within your budget constraints.

Best email service providers on the market

Determining the best email service providers is subjective. It depends on the specific needs and preferences of the user or organization. However, there are several providers that are recognized for their quality, reliability, and range of features. Here are some of the top contenders.


The Selzy home page, featuring a headline that says, “The easiest way to start selling with emails.”

Selzy is known for its user-friendly interface and customizable templates. This makes it ideal for small to medium-sized businesses that might be new to email marketing or might not have the means to afford to spend a considerable portion of their resources on it. 

The service offers segmentation options and personalized email campaigns. In other words, it allows you to send messages that are tailored to your customers. For example, you could address your customer by name in a subject line using tags. What’s more, you could do it automatically, without having to check and type in their name manually. 

Additionally, Selzy provides detailed analytics and the ability to A/B test campaigns. These tools are bound to help you determine what resonates with your audience and what doesn’t. Aside from that, Selzy is completely free to use with some limitations. And if you ever feel like upgrading, the cheapest paid tier starts from just $7 a month.


The Mailchimp home page, featuring a headline that says, “Turn emails into revenue.”

Mailchimp is a widely recognized email service provider, popular for its easy-to-use design tools. It includes features like audience segmentation, automated marketing campaigns, and detailed reporting tools. What’s more, Mailchimp can connect with numerous third-party applications, such as lead generation software and graphic design tools. The pricing starts at $13 a month for 500 contacts.

Constant Contact

The Constant Contact home page, featuring a headline that says, “Take your marketing from meh to marvelous.”

Constant Contact stands out for its extensive library of more than five thousand integrations with different third-party tools, from lead generation software to graphic design tools. It’s particularly user-friendly for beginners, offering drag-and-drop editing tools and real-time email tracking. The platform also provides social media integration, making it a great choice if you are running marketing campaigns on multiple social media platforms at the same time. You will have to pay at least $12 a month to start using it, as that’s the price of their cheapest paid tier.

Campaign Monitor

The Campaign Monitor home page, featuring a headline that says, “Drive results with unforgettable email marketing.”

Campaign Monitor stands out with its no-code email editor. With it, you can customize your emails without any knowledge of CSS or HTML. The platform also offers advanced segmentation and detailed analytics. As a result, it caters to both small businesses and larger enterprises. You can use it to learn how email marketing works, as well as to launch and manage large-scale campaigns. Again, just like Constant Contact, it’s not free. The pricing starts from $11 a month.


The Klaviyo home page, featuring a headline that says, “Power smarter digital relationships.”

Klaviyo is a top choice for e-commerce businesses, integrating seamlessly with e-commerce platforms like Shopify. The service excels in data-driven email marketing. It allows users to create highly targeted campaigns based on customer behavior. This makes it a powerful tool for driving sales and customer engagement. You can start using Klaviyo for free, and if you’d like to upgrade, the cheapest paid tier starts at $30 a month.

Final thoughts

An email service provider is more than just a tool for sending and receiving emails. It is a critical component in the strategic communication and sales generation efforts of any business type, from e-commerce giants and mid-sized marketing agencies to mom-and-pop stores. So, when choosing an email service provider, make sure to think things through. How much are you willing to pay? What features matter to you the most? Then, carefully explore the options that are available to you. To make things easier, consider the following key points.

  • Deliverability and performance. Ensure the ESP has a strong track record for delivering emails effectively.
  • Security and compliance. Look for security features and compliance with data protection regulations.
  • Cost-effectiveness and scalability. Choose an ESP that offers scalable solutions at a cost-effective price.

Remember, the best ESP for your business is one that aligns with your communication goals, offers the necessary features and support, and fits within your budget. By carefully evaluating these aspects, you can select an ESP that not only meets your current needs, but also supports your business’s growth and evolution in the long term.

18 December, 2023
Article by
Sara Kurczyńska
Sara Kurczyńska is an experienced content writer from Poznań, Poland. She enjoys writing about digital marketing, as well as playing video games and petting her fancy rats. In her spare time, you can find her birdwatching and taking long walks around the local parks and forests.
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