(Perl) 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.

Chilkat Perl Downloads Perl Module for Windows, MacOS, Linux, Alpine Linux, Solaris

use chilkat();

# 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 = chilkat::CkMailMan->new();

# The dkim object is used for creating the DKIM signature.
$dkim = chilkat::CkDkim->new();

# 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 = chilkat::CkEmail->new();

$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 = chilkat::CkByteData->new();
$success = $mailman->RenderToMimeBytes($email,$mimeData);
if ($success != 1) {
    print $mailman->lastErrorText() . "\r\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 = chilkat::CkPrivateKey->new();
$success = $privKey->LoadAnyFormatFile("myPrivateKey.pem",$password);
if ($success != 1) {
    print $privKey->lastErrorText() . "\r\n";
    exit;
}

$success = $dkim->SetDkimPrivateKey($privKey);
if ($success != 1) {
    print $dkim->lastErrorText() . "\r\n";
    exit;
}

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

$success = $dkim->AddDkimSignature($mimeData,$dkimSignedMime);
if ($success != 1) {
    print $dkim->lastErrorText() . "\r\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 != 1) {
    print $mailman->lastErrorText() . "\r\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 != 1) {
    print "Connection to SMTP server not closed cleanly." . "\r\n";
}

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