Implementing SMTP LANG with proxy script – Halon

The upcoming Halon 5.1 release introduces a new SMTP server proxy script. It’s configured to be executed before specific (or all) SMTP commands, even command which isn’t recognised by the SMTP server. In this blog we’ll describe how to implement our proposed SMTP LANG extension using this new script hook. First of all, we announce the LANG extension and the languages supported in the HELO script:

$announce =  [...$arguments["extensions"], "LANG SE"];
Accept(["extensions" => $announce]);

Next, we configure to proxy script to hook onto the new “BREV”, “INNEHÅLL” and “HEJDÅ” commands:

Finally, we setup the proxy script to translate the international (Swedish, in this case) commands with their standard SMTP respective:

$cmd = str_upper($arguments["command"]);
if ($cmd[0:11] == "BREV FRÅN:") { // MAIL FROM
    $realcmd = "MAIL FROM:" + $arguments["command"][11:];
    Pass(["command" => $realcmd]);
}
if ($cmd == "HEJDÅ") { // QUIT
    $codes = ["code" => 221, "enhanced" => [2, 0, 0]];
    Reply("Ha det bra", ["reply_codes" => $codes, "disconnect" => true]);
}
// etc...

The proxy script and the corresponding xtext functions can be used for many other things, like custom XCLIENT implementations. More information on the 5.1 will be released later this month.