cPanel

cPanel is a Linux based web hosting control panel that provides a graphical interface and automation tools designed to simplify the process of hosting a web site.

Many of our customers uses the Halon platform as a premium anti-spam in front of their cPanel servers. There are numerous different integration opportunities, and our official plugins only scratch the surface of what's possible. Most advanced integration are co-developed by us and the hosting provider, on a project basis.

One-click end-user login

The end-user control panel supports on-the-fly (session-based) access levels (domain or email based), which our cPanel module can prepare via the session-transfer.php file.

Fetching cPanel information

You might want the end-user control panel to fetch some information from the cPanel API, such as Email::list_forwarders. We've done numerous such integrations, and can help you tailor the systems to fit perfectly.

Dynamic routing

A fast and simple solution to get started with Halon and cPanel is to use a dynamic routing where we check the mail hostname for the recipients domain, e.g. mail.example.com. If the IP address is one of our cPanel servers we will use it to make recipient lookup and then transport all mail to the fully qualified domain name.

You need to make sure that the cPanel's email routing is set to Local Mail Exchanger under the Email Routing -> Configure Email Routing page.

Note: If your cPanel environment don't use a common hostname that points to the correct cPanel server then you will need to create one and modify the code. By default cPanel adds this hostname with the cPanel's IP address.

To get started, create a new plain-text file under Configuration -> Email engine -> Code editor with the ID cpanelnetwork. Now add all IP addresses to your cPanel servers, separated by a line. It's also possible to use a subnet mask e.g. 10.0.0.0/24.

Now create one more file (code) with the ID cpanelrouting and add this script to it.

function lookup_cpanelserver ($recipientdomain) {
    $fqdn = "mail." + $recipientdomain;
    $ips = dns($fqdn);
    if (!$ips) return 0;
    foreach (file("file:cpanelnetwork") as $cpanelnetwork) {
        if (in_network($ips[0], $cpanelnetwork)) {
            echo "Found matching cpanel server for " + $fqdn + " (" + $ips[0] + ")";
            return $fqdn;
        }
    }
    return 0;
}

In the RCPT TO context under Configuration -> Email engine -> Script mappings, add this code to enable the lookups against your cPanel servers.

include_once "file:cpanelrouting";

// Dynamic recipient lookup
$cpanelserver = cache ["ttl" => 3600, "size" => 2048, "ttl_override" => [0 => 1800]] lookup_cpanelserver($recipientdomain);

if ($cpanelserver) {
    $result = cache [
            "ttl_function" => function ($result) {
                $code = $result["error_code"];
                if ($code == -1)
                    return 60;
                if ($code >= 200 and $code <= 299)
                    return 86400;
                return 300;
            },
            "size"=> 16384,
        ]
        smtp_lookup_rcpt(["host" => $cpanelserver], "", $recipient, ["error_code" => true]);
    if ($result["error_code"] == -1) {
        $error = true;
        $errormsg = "SMTP recipient lookup failed";
    }
    if ($result["error_code"] >= 200 and $result["error_code"] <= 299) {
        $context["dynamicroute"] = true;
        Accept();
    }
    if ($result["error_code"] >= 400 and $result["error_code"] <= 499)
        $error = true;
    if ($result["error_code"] >= 400 and $result["error_code"] <= 599)
        $errormsg = $result["error_message"];

    if ($error ?? false)
        Defer($errormsg ?? "");
    else
        Reject($errormsg ?? "");
}

Now to finalize the integration you need to add two more parts to your incoming flow. In the DATA context add this line at the top of the page.

if ($context["dynamicroute"] == true) {
    SetMetaData(["dynamicroute" => "yes"]);
}

And in the pre-delivery context under Configuration -> Email engine -> Code editor you need to add this code so it can deliver it to the correct server.

include_once "file:cpanelrouting";

$metadata = GetMetaData();

if ($metadata["dynamicroute"] == "yes") {
    $cpanelserver = cache ["ttl" => 3600, "size" => 2048, "ttl_override" => [0 => 1800]] lookup_cpanelserver($recipientdomain);
    if (!$cpanelserver) 
        Reschedule(rand(1, 300), ["reason" => "Mailserver for $recipientdomain not found", "increment_retry" => false]);
    SetDestination($cpanelserver);
    Try();
}

If you don't find a pre-delivery script you will need to create it, click on the add button and choose pre-delivery as type.