DKIM with Nette Mail - email

Question

I planned to sign my mails with php-mail-signature (https://github.com/louisameline/php-mail-signature), but I can't find a method in the Nette-Mail Message class (https://api.nette.org/2.4/Nette.Mail.Message.html) to set the DKIM-value.
Since I thought that would be more or less basic functionality, I'm wondering if it really isn't possible to use DKIM with Nette Mail.
Is it possible, and if so, how do I do it?

Answer 1

Problem is, php-mail-signature is too much low-level. It returns signed headers as string. You need to parse $signature->get_signed_headers() output and call $message->setHeader() for each of them. If you're looking for some magic method $message->setDkimSignature(), you won't find it. But you can always inherit from Message class and write your own.
This is only non-tested example:
<?php
use mail_signature;
use Nette\Mail\Message;
final class DkimSignedMessage extends Message
{
/**
* #var mail_signature
*/
private $signature;
public function __construct(mail_signature $signature)
{
$this->signature = $signature;
}
public function generateMessage(): string
{
$message = $this->build();
$signedHeaders = $this->signature->get_signed_headers(
$message->getTo(),
$message->getSubject(),
$message->getBody(),
implode("\r\n", $message->getHeaders())
);
foreach (explode("\r\n", trim($signedHeaders)) as $header) {
[$name, $value] = explode(': ', $header);
$message->setHeader($name, trim($value))
}
return $message->getEncodedMessage();
}
}