setFrom('from@example.com', 'First Last'); //Set an alternative reply-to address $mail->addReplyTo('replyto@example.com', 'First Last'); //Set who the message is to be sent to $mail->addAddress('whoto@example.com', 'John Doe'); //Set the subject line $mail->Subject = 'PHPMailer DKIM test'; //This should be the same as the domain of your From address $mail->DKIM_domain = 'example.com'; //Path to your private key file $mail->DKIM_private = 'dkim_private.pem'; //Set this to your own selector $mail->DKIM_selector = 'phpmailer'; //If your private key has a passphrase, set it here $mail->DKIM_passphrase = ''; //The identity you're signing as - usually your From address $mail->DKIM_identity = $mail->From; //send the message, check for errors if (!$mail->send()) { echo "Mailer Error: " . $mail->ErrorInfo; } else { echo "Message sent!"; }