How to sign outgoing emails in Laravel 9 with a DKIM signature - dkim

Question

Please explain conception how to sign outgoing emails in Laravel 9 with a DKIM signature. Laravel 9 uses Symfony mailer. I'm trying to proceed by this way:
class ContactForm extends Mailable
{
use Queueable, SerializesModels;
public $mailData;
public function __construct($mailData)
{
$this->mailData = $mailData;
}
public function build()
{
$this->subject($this->mailData['subject'])
->view('mail.contact-form')
->text('mail.contact-form_plain');
$this->withSymfonyMessage(function (Email $message) {
$signer = new DkimSigner(config('mail.dkim_private_key'), config('mail.dkim_domain'),
config('mail.dkim_selector'));
$signer->sign($message);
});
return $this;
}
}
Error
local.ERROR: A message must have a text or an HTML part or
attachments. {"exception":"[object]
(Symfony\Component\Mime\Exception\LogicException(code: 0): A
message must have a text or an HTML part or attachments. at
E:\WebProjects\domains\hostbrook\vendor\symfony\mime\Email.php:390)

Answer 1

There is other way to sign outgoing emails in Laravel 9 with a DKIM signature (without any tool):
class ContactForm extends Mailable
{
use Queueable, SerializesModels;
public $mailData;
public function __construct($mailData)
{
$this->mailData = $mailData;
}
public function build()
{
$mailData = $this->mailData;
$htmlView = 'mail.contact-form';
$plainView = 'mail.contact-form_plain';
$htmlEmail = view($htmlView, compact('mailData'))->render();
$plainEmail = view($plainView, compact('mailData'))->render();
return $this->subject($this->mailData['subject'])
->view($htmlView)
->text($plainView)
->withSymfonyMessage(function (Email $message) use ($htmlEmail, $plainEmail) {
$message
->html($htmlEmail)
->text($plainEmail);
$signer = new DkimSigner(
config('mail.dkim_private_key'),
config('mail.dkim_domain'),
config('mail.dkim_selector')
);
$signedEmail = $signer->sign($message);
$message->setHeaders($signedEmail->getHeaders());
});
}
}

Answer 2

There is a tool that will solve your problem. You can get it here and this is how you use it:
Install package with composer using: composer require simonschaufi/laravel-dkim
In the config/app.php file, comment Illuminate\Mail\MailServiceProvider::class line and add the following line with dkim package service provider: SimonSchaufi\LaravelDKIM\DKIMMailServiceProvider::class
Publish the config file using the artisan command: php artisan vendor:publish --provider="SimonSchaufi\LaravelDKIM\DKIMMailServiceProvider"
Configure your dkim settings in your .env file:
DKIM_PRIVATE_KEY=your_txt_private_key_path // Required. Indicates your private key txt file configured previously. By default, the storage path app/dkim/private_key.txt is used
DKIM_SELECTOR=your_dkim_record_selector // Required. If this value is empty, <code>default</code> is used
DKIM_DOMAIN=your_dkim_domain // Required. Indicates the domain of your dkim record configured previously
DKIM_PASSPHRASE=your_dkim_passphrase // Optional
DKIM_ALGORITHM=your_dkim_algorithm // Required. By default, rsa-sha256 is used
DKIM_IDENTITY=your_dkim_identity // Optional
This tool solves the problem using a custom Mailer with dkim signature:
$signer = new DkimSigner(file_get_contents($privateKey), $domain, $selector, [], config('dkim.passphrase'));
$signedEmail = $signer->sign($message->getSymfonyMessage());
$symfonyMessage->setHeaders($signedEmail->getHeaders());