If you want to ensure that your transactional emails are successfully delivered, using a specialized SMTP service is essential. SMTP is a widely used protocol for sending and receiving emails over the internet, and it offers a secure way to send messages with email authentication that can help ensure delivery to your recipients' inboxes.

An SMTP service enables you to connect to an SMTP server using an email client or web application enabling you to oversee both incoming and outgoing emails. Although free SMTP services like Gmail, Outlook, and GoDaddy are available, they often have limitations on the number of messages you can send.

Choosing the perfect SMTP service can be a challenging task, given the wide range of available options. However, it's vital to pinpoint the essential features that match your business requirements. In this article, we'll highlight the top 5 SMTP services and provide a guide to help you identify the essential features to look for when selecting the best SMTP service for your business.

1. Mailtrap

Mailtrap is an all-in-one email delivery platform that caters to both individuals and businesses, offering comprehensive testing, sending, and in-depth analytics to gauge email performance. With Mailtrap's Email API/SMTP, developers can enjoy a reliable email infrastructure and maintain full control over their email deliverability. The platform's distinctive monitoring capabilities ensure smooth maintenance and troubleshooting. Moreover, Mailtrap has a proven track record of providing excellent customer support and guidance to assist users in utilizing its features optimally and resolving any challenges that may arise.


  • The Email API offers two sending options: Email API and SMTP Service
  • The platform provides actionable, in-depth analytics with a comprehensive dashboard that displays all significant email performance metrics at a glance
  • Detailed logs of up to 60 days are available to monitor email history extensively
  • Deliverability alerts notify users of unexpected sending issues, enabling them to fix them before any complaints arise
  • The Email Sandbox feature provides a secure testing environment for emails before they go live in the production stage
  • Users can create multiple inboxes for different projects and stages, such as an Email Sandbox.


  • Free
  • Individual – $14.99 per month
  • Team – $34.99 per month
  • Business – $64.99 per month
  • Premium – $129.99 per month
  • Enterprise – $399.99 per month

2. Postmark

Postmark is a well-regarded SMTP service that stands out for its ease of use, emphasis on deliverability, and reliable customer support. Although it is relatively expensive compared to other options, it provides a comprehensive feature set, along with detailed documentation and webinars.


  • The SMTP service has a global reach with maintained endpoints in different regions worldwide
  • Users can access the Email API through several official SDKs
  • The platform's Message Streams feature enables sending of both transactional and broadcast messages
  • The Rebound feature notifies users when their email address requires updating
  • High volume senders have the option to obtain a dedicated IP address.


  • Start at – $15.00 per month

3. MailerSend

MailerSend is a sophisticated transactional messaging service designed for developers, offering an advanced SMTP integration feature. The platform also boasts an intuitive interface, making it easy for non-technical users to contribute. Developed by the creators of MailerLite, MailerSend is built by deliverability experts with more than a decade of experience in the email industry. Additionally, the platform provides award-winning customer support, ensuring a secure and reliable service that users can seamlessly navigate.


  • The platform provides a fast and reliable SMTP service that is optimized for deliverability and easy scalability
  • It offers a flexible and powerful API, which includes 7 regularly updated SDK libraries
  • The Inbound routing feature allows users to parse incoming messages to their application
  • The platform offers rich-text, HTML, and Drag & Drop email editors
  • It includes an inbuilt email verification tool, which validates recipients' email addresses before sending to them
  • The platform offers extensive user management tools, including custom roles and options for each team member
  • It also supports transactional SMS, enabling users to reach more customers in the most suitable way
  • Users can sign in via SSO and connect their MailerSend, MailerLite, and MailerCheck accounts
  • Dedicated IP addresses are available for high volume senders.


  • Free
  • Premium – $25.00 per month
  • Enterprise – Contact sale

4. Mailgun

Mailgun is an email service provider specifically designed for developers, with a strong emphasis on their email API. Although they do offer SMTP integration, Mailgun's focus is on transactional email sending, rather than email marketing. As a result, the platform's sending infrastructure appears to be optimized for reliability and deliverability.


  • Comes with built-in email verification tools to ensure deliverability of emails
  • Offers an advanced email API that supports multiple programming languages
  • Provides SMTP integration and comprehensive documentation
  • Offers live chat support for quick and easy assistance
  • Send Time Optimization feature holds emails until recipients are more likely to view them
  • Dedicated IP address available as an add-on for high volume senders


  • Free
  • Foundation – $35.00 per month
  • Scale – $90.00 per month
  • Custom – Contact sale

5. Mailchimp

Mailchimp is a widely-used marketing service that provides SMTP transactional email as a paid add-on (previously known as Mandrill). In addition to its email marketing services, Mailchimp has expanded its offerings to include a variety of digital marketing tools such as CRM, website building, advertising, and social media management.


  • All-in-one marketing platform for transactional email, email marketing and more
  • Capability to send emails through SMTP or API
  • Includes ROI (Return On Investment) tracking for email campaigns
  • Offers A/B testing support to optimize email performance
  • Dedicated IP address available for high-volume senders


  • Free
  • Core – $10.00 per month
  • Plus – $29.00 per month


To achieve secure, fast, and reliable email delivery at scale, implementing SMTP is a recommended option. This list of top SMTP services includes options for different budgets and needs, ranging from basic and straightforward services to more advanced transactional email solutions and comprehensive marketing tools. Therefore, every business can find a suitable solution. Furthermore, these services provide an opportunity to start with SMTP and eventually upgrade to an email API as you become ready for more advanced features.

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