SMTP sending made painless
SMTP relay services are one of the oldest methods of sending email, and there's a reason senders around the world still use them today to send business critical emails. Sending email via SMTP is a reliable and fast way to deliver email messages.
With the ability to scale seamlessly, Mailgun's SMTP infrastructure can handle any email volume while maintaining performance – providing you the foundation to build world-class deliverability without the hassle of in-house service management.


What is an SMTP relay?
A Simple Mail Transfer Protocol (SMTP) is a form of communication between two servers used to send and receive email.
When SMTP servers transfer messages across one another, an SMTP relay is performed. A SMTP port will be selected as the communication channel, and then the relay will be attempted. It’s important to note that not all ports have the same reputation and using the wrong one can land you in the spam folder. Fortunately, Maigun offers multiple SMTP port options to help you preserve sender reputation and deliverability.
Mailgun SMTP server features
Email API
Our RESTful email API helps businesses programmatically send, receive, and track emails at scale, ensuring efficient communication and seamless workflow integration.
Email Logs
Maintain a comprehensive record of all your email activity with detailed email logs. Track every sent, received, bounced, or dropped email with timestamps and detailed information.
Email Event Webhooks
Push email campaign data to other apps for cross-team insights, enabling real-time, data-driven decisions to improve email performance.
Email Routing
Route and parse incoming email streams in UTF-8 JSON for easier integration into systems, using an MTA designed for high-volume email delivery, streamlining data processing.
Email Protection
Email authentication and TLS encryption secure email transmission, protecting sensitive data and ensuring compliance.
Send Time Optimization
Send email campaigns when recipients are most likely to engage – boosting visibility, increasing engagement, and maximizing impact.
Land more emails in inboxes
Secure SMTP email streams keep spammers from spoofing your brand with proper authentication protocols. With protocols like SPF, DMARC, and DKIM records, you’ll not only improve the reputation of your brand with recipients but with inbox service providers too. Using these methods alongside solutions like our Email Address Validations, Inbox Placement Testing, and Send Time Optimization lowers your spam rate, reduces spam complaints, and improves your overall email deliverability.


Pair with your local SMTP email server
An SMTP email service offers useful benefits even if you have your own email server. As a result of pairing an SMTP service with internal servers, your application will see better performance because it hands off the sent emails to the local server, while your distribution still gets the benefit of a robust SMTP provider.
SMTP LOGS & ANALYTICS
Understand & improve email performance
Optimize email campaign performance with detailed reporting
Get advanced insights into your email performance with in-depth reporting features like multidimensional data views and custom filtering options. These tools allow you to examine your campaigns from multiple perspectives and pinpoint areas for improvement. The detailed reporting capabilities also include the ability to schedule, save, and send custom reports to stakeholders, streamlining data sharing and decision-making.
Track engagement levels through proactive monitoring
Gain real-time insights into how your recipients interact with emails using engagement validation data for proactive monitoring. With advanced tools that segment contacts by engagement levels, you can refine your targeting and improve overall campaign performance. This proactive approach helps identify trends and optimize your strategy to reduce bounce rates, ensuring better email deliverability and enhanced interaction with your audience.
Selecting an SMTP service
With Mailgun’s cloud-based SMTP server, send transactional email and email marketing campaigns to as many customers as you like without needing to support your own SMTP server. Mailgun is designed to help businesses of all sizes improve deliverability.
Easy integration and setup
Robust features, support, and analytics
Free SMTP server plans available for up to 100 emails/day


Setting up SMTP relay with Mailgun
One of the best things about an SMTP relay service is how easy it is to set up. Whether you’re working with a WordPress site or a custom domain, get started in just a few steps:
Add and verify your domain name: While your domain is being verified, send a test email from your sandbox domain to get a feel for Mailgun.
Configure your account: Add your username, password, SMTP server host name, and SMTP port into your application’s configuration settings, and you’re ready.
Start sending emails: Improve security by adding a regular or SSL connection, depending on which port you use.
“With Mailgun, we don’t have to think about email. It’s easy, it works and it’s affordable. It allows us to focus on business goals. Mailgun works when our client is really small and it scales to fit them when they become really large.”
Nick Frandsen
Partner at Dovetail