Dart

Send DKIM Signed Email

See more DKIM / DomainKey Examples

Demonstrates how to send DKIM signed email. Dart

import 'package:chilkat/chilkat.dart';

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

  final mailman = CkMailMan();
  final dkim = CkDkim();

  // SMTP server settings...
  mailman.smtpHost = 'SMTP_DOMAIN';
  mailman.smtpUsername = 'SMTP_LOGIN';
  mailman.smtpPassword = 'SMTP_PASSWORD';
  mailman.smtpPort = 465;
  mailman.smtpSsl = true;

  final email = CkEmail();

  email.subject = 'This is a test';
  email.body = 'This is a test';
  email.from = 'Chilkat Support <support@chilkatsoft.com>';

  // Add some recipients (BCC recipients are added below)
  email.addTo('Chilkat Software', 'chilkat_software@yahoo.com');
  email.addTo('Chilkat Admin', 'admin@chilkatsoft.com');
  email.addCC('Chilkat Admin', 'admin@chilkat.io');

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

  // First get the MIME of the email.  Calling RenderToMimeBd 
  // causes the email to be signed and/or encrypted if those options
  // have been selected.  The MIME returned by RenderToMimeBd
  // 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...
  final bdMime = CkBinData();
  try {
    mailman.renderToMimeBd(email, bdMime);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // To create a DKIM signature,
  // 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.dkimDomain = 'chilkatsoft.com';
  dkim.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
  // an empty password string argument, but it is ignored.
  final password = 'passwd';
  final privKey = CkPrivateKey();
  try {
    privKey.loadAnyFormatFile('qa_data/pem/rsa_passwd.pem', password);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  try {
    dkim.setDkimPrivateKey(privKey);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Add the DKIM-Signature header to the MIME in bdMime
  try {
    dkim.dkimSign(bdMime);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // If desired, examine the MIME of the email being sent.
  bdMime.writeFile('qa_output/dkimSigned.eml');

  // ---- Prepare to send the email contained in bdMime ---

  // To send to multiple email addresses, the strRecipients should be set to a comma-separated
  // list of email addresses.

  // Note: This is where we can add additional BCC addreses.
  // Here we are adding "chilkat.support@gmail.com" as an additional BCC address.
  // Notice that the 1st three email addresses are NOT BCC because these email addresses
  // appear in the MIME header of the email (in the "To" and "CC" header fields).
  // A BCC email address does not appear in the MIME, and thus the non-BCC recipients cannot see
  // that the email was also sent to the BCC address.  (BCC means "blind carbon copy")
  final strRecipients = 'chilkat_software@yahoo.com, admin@chilkatsoft.com, admin@chilkat.io, chilkat.support@gmail.com';
  final strFrom = 'support@chilkatsoft.com';

  try {
    mailman.sendMimeBd(strFrom, strRecipients, bdMime);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  try {
    mailman.closeSmtpConnection();
  } on ChilkatException {
    print('Connection to SMTP server not closed cleanly.');
  }

  print('DKIM Signed Mail Sent!');
}