The ultimate guide to Mail Transfer Agents (MTAs)

If your business is responsible for sending large volumes of emails each month, your primary concern should be choosing a reliable mail transfer agent (MTA) that can handle the task. Selecting the right MTA can significantly impact the deliverability and overall success of your email campaigns, helping you deliver a best-in-class customer experience that will keep customers loyal and enable you to scale your business.


What is a mail transfer agent (MTA)?

A mail transfer agent, also known as an MTA, is a software application that routes emails between the sender and the receiver. MTAs play a vital role in ensuring the smooth flow of emails around the world. They act as intermediaries between different email servers and are responsible for handling all aspects of message transmission.

An MTA (Mail Transfer Agent) receives emails either from another MTA or from a Mail User Agent (MUA). An MUA is a software application that enables end users to access and send emails. When an MUA forwards an email to an MTA, the MTA is responsible for delivering it to the recipient's MTA using the Simple Mail Transfer Protocol (SMTP). 

A best-in-class MTA helps your business to ensure reliable and efficient delivery of your emails. Without an MTA, your email would have no way of reaching its intended recipient. An MTA is responsible for verifying the recipient's address, routing the email to the correct server, and handling any errors or delays that may occur during transmission.

There are many different MTAs available, each with its own unique set of features and capabilities. But why should you care about an MTA? Let’s review the purpose of an MTA in more detail, so you can evaluate what makes the most sense for your business needs.


Benefits of using a mail transfer agent

As a large-scale sender or martech provider, you can reap the following rewards with a best-in-class MTA:

• Scalability and performance optimization
  Halon offers high-performance with automatic scalability based on demand, whether you’re using cloud-based or on-premise infrastructure. By leveraging a public cloud, you can utilize Halon's autoscale feature to efficiently scale up during peak send periods without investing in additional hardware or resources. This means you can easily handle large volumes of emails and maintain the same level of performance, even during high traffic times such as Black Friday or Cyber Monday.
• Reliable email delivery and queuing
  When you’re responsible for sending a large volume of emails, it’s important to set up conditional workflows to optimize your delivery rates and protect your sender reputation. Halon comes with a powerful policy engine, where you can set up custom rules to determine when and how emails are sent and received. With granular traffic segregation, you can ensure that your messages are prioritized accordingly to maximize deliverability.
• Enhanced email security and spam prevention
  You need to put measures in place to protect against incoming phishing attacks and spam, while also preventing your own customers' emails from being marked as spam. Halon offers advanced email security features such as SPF, DKIM, DMARC, and TLS encryption to ensure that all outgoing messages are authenticated and encrypted for secure delivery. With the ability to automatically quarantine or discard suspicious messages, you can maintain a high level of trust with your customers and reduce the risk of getting blacklisted by ISPs. Halon offers email integrations with many leading anti-spam and anti-virus engines, so that you can bring together the right components for a highly secure email infrastructure that meets your customers’ needs.
• Intelligent email routing and error handling
  Stay in control of your email delivery, bounce processing, and logging. Halon includes advanced routing capabilities that allow you to easily manage different types of email messages and their destinations. In addition, our error handling features ensure that any issues with your email delivery are promptly identified and resolved. This helps you maintain a high level of customer satisfaction and prevent potential blacklisting by ISPs.
• Detailed analytics and reporting capabilities
  With Halon’s Delivery Insights, you can tap into comprehensive reporting and analytical insights. Monitor key success metrics including delivery, queuing, bounce rates, and performance closely by setting alerts. Directly address issues by initiating, halting, and adjusting email behaviors right from the user interface. You can also integrate the platform with external data analytics solutions, so you can get a fuller picture of your business performance.

Challenges in MTA deployment

Migrating to a new MTA can pay off in terms of improved performance and deliverability, but it’s important to understand the challenges in deploying a new solution.

The process can involve complex configuration and management, so be sure to bring on the right internal resources with experience in deploying and managing similar solutions, and ensure that you’ve set up an optimized mix of components to power your infrastructure. Choose a solution that can integrate with your existing infrastructure and applications, has the scalability to handle peak email volumes, and includes best-in-class anti-virus and anti-spam applications to maintain customer security and prevent abuse. 

By conducting a phased migration, and moving your customer base to the new platform in segmented groups, you’ll be able to reduce the likelihood of errors impacting your entire customer base.

Choosing an open-source solution means that you’re on your own when it comes to support. But partnering with a best-in-class infrastructure provider like Halon gives you access to expert technical support as well as a vast library of ready-made components and technical documentation. Our wealth of resources and support will ensure that you’ll always have access to guidance to help you architect a customized solution that meets your business needs.


Comparison: On-premise MTA vs. Cloud-based SMTP relay

Should you operate your own MTA infrastructure?

While there are a number of cloud-based APIs to choose from, you’re likely to achieve the best performance and deliverability rates by operating your own email infrastructure. Rather than relying on a third-party vendor and dealing with their restrictions, you can architect a customized solution that includes all of the features that you need, and leaves out the ones you don’t. 

By empowering your development team to build a proprietary solution, you’ll be equipped to set customized rules for email dispatches and receipt that will help you improve deliverability, reduce spam and abuse, and ensure high performance, in a secure, controlled environment. You’ll also gain access to data insights that you can use to optimize your email strategy and make informed decisions to improve business operations.

While a cloud-based API may be sufficient for smaller senders, as your business scales, you’ll need the control and performance that comes with operating your own MTA. 

Best practices when choosing an MTA provider

When you’re selecting an MTA provider, consider all of these factors:

1. Scalability
Choose a solution that uses cloud-based load balancing, enabling each instance to effortlessly manage email delivery across any IP strategy. This ensures immediate scalability and reliability, guaranteeing peak performance at all times. Halon offers a scalable email infrastructure that works seamlessly for both on-premise and cloud-based installations. 

2. Security
Keep your customers -and your sender reputation -safe by providing best-in-class cybersecurity protection. Your solution should seamlessly integrate with a wide array of applications, databases, and reporting tools to mitigate cybersecurity threats effectively. See Halon’s integrations here. 

3. Deliverability
Mastering email deliverability with the right strategies and tools is easy with Halon. Improve deliverability with a solution that uses intelligent queue management and IP warming strategies to enhance email reach and inbox placement. Halon’s policy engine gives you unmatched control in setting up delivery rules to ensure your platform is optimized for success.

4. Ease of integration
Make sure that you’ll be able to set up a tech stack that supports all of your custom business needs. With Halon, developers can create custom-designed plugins to accommodate unique code or non-standard protocols, enabling tailored solutions for specific needs. Halon can easily integrate with CRM platforms, inventory and fulfillment platforms, and ecosystems like Microsoft 365, ensuring that your email delivery is seamlessly integrated with your other business operations.

5. Performance and reliability
Your customers may be sending 10s of thousands of concurrent messages per instance and it’s essential that your MTA is up to the task, without any interruptions during high-traffic peaks. Halon’s Ultra IO component makes it possible to process high volumes of email transactions with fewer deferrals and less latency, providing unmatched delivery speed and reliability. Mailkit noticed a 50% faster time-to-market and 20% reduction in code after making the switch to Halon. 

6. Delivery insights
Your solution should provide access to a wealth of data insights regarding key metrics including delivery updates, message failures, average transfer time, messages in queue, and more. You should be able to set up customized alerts when metrics go beyond certain thresholds, so you can immediately take action and resolve delivery or abuse issues. Halon’s customized dashboard empowers you to create your own customized dashboards that you can configure with the reports you need, making it easy to act on your data.

Image source: Halon

7. Quality customer support
Rather than choosing an open-source solution and navigating the hurdles of implementation on your own, choosing a premium solution like Halon will give you access to expert-led support and a robust collection of ready-made components that your development team can use to seamlessly architect a world-class solution that’s customized to your needs. We offer expert customer support, as well as a large network of self-service resources, including a knowledge base, script reference, a module library, and more, ensuring that you can find the resources you need at your fingertips. Learn more about the benefits of choosing Halon over an open-source solution.

Choose the right MTA with Halon

Selecting an MTA is the most important choice you’ll make in setting up your email infrastructure. Choosing a high-performing MTA will ensure that you can maximize delivery rates and delivery speed for all of your customers, while protecting their inboxes from abuse and spam. Delivering a best-in-class experience for your customers starts with selecting a leading email infrastructure solution.

Halon is the leading email infrastructure designed to enhance the customer email experience while lowering operational expenses. Halon’s infrastructure provides you with full control over your delivery, plus our ready-made components and integrations give you the tools to set up a customized email infrastructure that suits your business needs. Halon empowers you to deliver a top-tier customer experience unmatched by any other email infrastructure solution. 

You can enhance email delivery and engagement with Halon Engage, and secure email services with Halon Protect for mailbox providers.

Ready to learn more about why Halon is the clear choice for your email infrastructure needs? Book a demo today.