The flexible MTA for senders and ESPs

Large senders of transactional or marketing email need an MTA that enables them to develop great solutions in a highly competitive market. Halon provides outstanding integration capabilities, reliability and performance; ideal for organisations with sophisticated email delivery needs.

Features Contact us
Challenges and benefits
  • Highly flexible. Lack of flexibility in the MTA can lead to compromises and complexity, resulting in high maintenance costs and risks. The Halon MTA can be tailored to specific needs, allowing for virtually unlimited customisation. It is scriptable and extensible, but lean and compact at the same time. It has integrated blue-green deployment and supports modern development processes.
  • Fully adaptable. Incorporating an alternative MTA into an existing environment can be challenging. The Halon MTA can be fully adapted to work seamlessly with surrounding infrastructure, which allows for a cost-effective and non-intrusive implementation.
  • Committed. The MTA is an integral part of the sender's operation; a business-critical component. Halon's only focus is to develop and support an MTA for large service providers. The Halon MTA is in active development with quarterly feature releases.
Built for email service providers

The most flexible email delivery platform

  • Greater scalability

    Highly efficient and using an asynchronous model, it can handle tens of thousands of concurrent connections and sustain blazing throughput, even in complex scenarios.

  • Management and integration

    Valuable real-time insights and full control of sending. Available via web, command line, and queue APIs that together with the scripting enables powerful integrations into your existing environment.

  • Signing and authentication

    Support for all the latest authentication standards; including SPF, DKIM, DMARC and ARC. Any settings, including keys and selectors, can be fetched from external data sources via scripting.

  • Latest encryption standards

    Supports the latest encryption standards such as MTA-STS, TLS-RPT, DANE, TLS 1.3, S/MIME, client certificates, as well as granular TLS protocol, cipher control and SNI.

  • Granular throttling

    Control concurrency and rate using any combination of parameters such as source IP, domain, MX, destination IP or other meta data. Those can be grouped using RegEx or wildcard to implement for example MX rollup.

  • Deliverability automation

    Throttles or suspends can be adjusted dynamically based on response patterns, bounces, queue metrics and much more. Infinitely tailorable using the Halon scripting language.

More features
Enables rapid development

Increase service competitiveness

Suffering from slow and costly implementation of email features and new standards, leading to poor end customer experience? Halon increases email service competitiveness by enabling rapid implementation and reliable deployment. In contrast to traditional layered email infrastructure, Halon's holistic approach cuts system complexity, and enables you to more quickly architect the system that you want without compromises.

Integrated blue-green deployment

Reduce deployment time and risks

Run parallel versions of your configuration with traffic splitting. Along with a consolidated and programmatic approach to in-transit email, you can make rapid implementations as well as reliable deployments of changes or new functionality. Revision-managed configuration makes all changes fully visible, and provides instant rollbacks.

Slideshow
  • The Halon MTA is a flexible email operations and security platform. It enables organisations that operate large-scale email services to offer competitive features by rapid implementation and to lower maintenance costs through reliable deployment and reduced complexity.
© 2022 Halon Security AB. Privacy policy. 
if ($message["transportid"] === "bounces")
    Try(["protocol" => "smtp"]); // Use SMTP for locally generated DSNs
// Use a more robust lookup like https://wiki.halon.io/API_calls
$route = cache ["ttl" => 3600] http("$apiurl/route", [], [$message["recipientaddress"]["domain"]]);
$route = json_decode($route);
if (!is_array($route))
    Queue(["delay" => 3600, "reason" => "Invalid route", "increment_retry" => false]);
Try(["protocol" => "lmtp", "server" => $route["storage"]]);

$options = [];
if (GetMetaData()["spam"] == "yes") {
    $options["sourceip"] = ["4"]; // Bulk IP
} else {
    // Source hash
    $addrs = ["1", "2", "3"];
    $sourcehash = number("0x".md5($message["senderaddress"]["domain"])[0:6]);
    $options["sourceip"] = [$addrs[$sourcehash % length($addrs)]];
}
Try($options);

// In the post-delivery script
$senderdomain = $message["senderaddress"]["domain"];
$errorcode = $arguments["attempt"]["result"]["code"];
if ($errorcode >= 400)
    rate("delivery-failures", $senderdomain, 1000, 3600);

// In the MAIL FROM script
$senderdomain = $arguments["address"]["domain"];
if (rate("delivery-failures", $senderdomain, 0, 3600) > 999)
    Defer("$senderdomain has more than 1000 failed deliveries during the last hour");

// Per-domain DKIM signing using external database
// Use a more robust lookup like https://wiki.halon.io/API_calls
$dkim = cache ["ttl" => 86400, "size"=> 32768, "ttl_override" => ["" => 60]]
    http("$apiurl/dkim/$1", ["timeout" => 10], [$transaction["senderaddress"]["domain"]]);
$dkim = json_decode($dkim);
if (is_array($dkim))
    $arguments["mail"]->signDKIM($dkim["selector"], $dkim["domain"], $dkim["rsakey"]);