Description DKIM1 is supported by the Mailer Component. There is also documentation2. Syntax use Symfony\Component\Mime\Crypto\DkimSigner; use Symfony\Component\Mime\Email; $email = (new Email()) ->from('[email protected]') // ... ->html('...'); $signer = new DkimSigner('file:///path/to/private-key.key', 'example.com', 'sf'); $signedEmail = $signer->sign($email); Footnotes Footnotes https://en.wikipedia.org/wiki/DomainKeys_Identified_Mail ↩ https://symfony.com/doc/master/mailer.html#dkim-signer ↩