(PHP Extension) Send DKIM Signed Email

Demonstrates how to create a simple email, add a DKIM signature, and send it.

Note: Requires version 9.0.3 or greater.

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<?php

// The version number (9_5_0) should match version of the Chilkat extension used, omitting the micro-version number.
// For example, if using Chilkat v9.5.0.48, then include as shown here:
include("chilkat_9_5_0.php");

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// The mailman object is used for sending and receiving email.
$mailman = new CkMailMan();

// The dkim object is used for creating the DKIM signature.
$dkim = new CkDkim();

// Set the SMTP server.
$mailman->put_SmtpHost('smtp.chilkatsoft.com');

// Set the SMTP login/password (if required)
$mailman->put_SmtpUsername('myLogin');
$mailman->put_SmtpPassword('myPassword');
// Set the SmtpPort if your SMTP server uses an alternative port (default = 25)
$mailman->put_SmtpPort(587);

// Create a new email object
$email = new CkEmail();

$email->put_Subject('This is a test');
$email->put_Body('This is a test');
$email->put_From('Chilkat Support <support@chilkatsoft.com>');
// We'll send the email to a Yahoo email account.  It is then
// possible to view the full headers within the Yahoo email
// interface to see if the DKIM signature was accepted.
$success = $email->AddTo('Chilkat Software','chilkat_software@yahoo.com');
$success = $email->AddTo('Chilkat Admin','admin@chilkatsoft.com');

// When sending an email with a DKIM signature, the MIME
// of the email must not be modified (in significant ways) prior to
// or during the sending process.  Therefore, the MIME of the
// email is assembled, the DKIM signature is added, and then
// SendMimeBytes is called to send the email.

// Get the MIME of the email.  Calling RenderToMimeBytes 
// causes the email to be signed and/or encrypted if those options
// have been selected.  The MIME returned by RenderToMimeBytes
// is the exact MIME that would've been sent if SendEmail was
// called.  We'll add a DKIM signature header to this MIME and then send...
$mimeData = new CkByteData();
$success = $mailman->RenderToMimeBytes($email,$mimeData);
if ($success != true) {
    print $mailman->lastErrorText() . "\n";
    exit;
}

// To create a DKIM signature for email (i.e. MIME),
// you'll need to provide the following:
// (1) An RSA private key in any common file format.
// (2) The domain name (typically the same domain
// as the sender of an email).
// (3) A selector for the domain name -- an arbitrary string
// to identify the matching public key in DNS.

// To allow an email recipient to verify the DKIM signature via an
// external email client supporting DKIM or using other software,
// you will need to create a DNS record with the selector
// and matching public key.  This example does not provide
// information about DKIM DNS record creation.  
// (Chilkat does not provide an API for creating DNS records.  
// Creating the DKIM DNS record is something you would do
// manually.)

// Set the domain and selector:
// You'll need to provide your own values here..
$dkim->put_DkimDomain('chilkatsoft.com');
$dkim->put_DkimSelector('brisbane');

// Load a private key from any common RSA private key
// format, such as DER, PKCS8, PEM, XML, etc.
// The LoadDkimPkFile method automatically detects
// the file format and reads it appropriately.
// If a password is not required, you'll still need to provide
// a password string argument, but it is ignored.
$password = 'optionalPassword';
$privKey = new CkPrivateKey();
$success = $privKey->LoadAnyFormatFile('myPrivateKey.pem',$password);
if ($success != true) {
    print $privKey->lastErrorText() . "\n";
    exit;
}

$success = $dkim->SetDkimPrivateKey($privKey);
if ($success != true) {
    print $dkim->lastErrorText() . "\n";
    exit;
}

// Add the DKIM-Signature header and
// returns the new MIME with DKIM-Signature added.
$dkimSignedMime = new CkByteData();

$success = $dkim->AddDkimSignature($mimeData,$dkimSignedMime);
if ($success != true) {
    print $dkim->lastErrorText() . "\n";
    exit;
}

// Call SendMimeBytes to connect to the SMTP server and send.
// The connection (i.e. session) to the SMTP server remains
// open so that subsequent Send* calls may use the
// same connection.  
$strFrom = 'support@chilkatsoft.com';
// To send to multiple email addresses, the strTo should be set to a comma-separated
// list of email addresses.
$strTo = 'chilkat_software@yahoo.com, admin@chilkatsoft.com';
$success = $mailman->SendMimeBytes($strFrom,$strTo,$dkimSignedMime);
if ($success != true) {
    print $mailman->lastErrorText() . "\n";
    exit;
}

// Some SMTP servers do not actually send the email until 
// the connection is closed.  In these cases, it is necessary to
// call CloseSmtpConnection for the mail to be  sent.  
// Most SMTP servers send the email immediately, and it is 
// not required to close the connection.  We'll close it here
// for the example:
$success = $mailman->CloseSmtpConnection();
if ($success != true) {
    print 'Connection to SMTP server not closed cleanly.' . "\n";
}

print 'DKIM Signed Mail Sent!' . "\n";

?>