(Java) Send DKIM Signed Email

Demonstrates how to send DKIM signed email.

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import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

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

    boolean success;
    CkMailMan mailman = new CkMailMan();
    CkDkim dkim = new CkDkim();

    // SMTP server settings...
    mailman.put_SmtpHost("SMTP_DOMAIN");
    mailman.put_SmtpUsername("SMTP_LOGIN");
    mailman.put_SmtpPassword("SMTP_PASSWORD");
    mailman.put_SmtpPort(465);
    mailman.put_SmtpSsl(true);

    CkEmail 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>");

    // 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...
    CkBinData bdMime = new CkBinData();
    success = mailman.RenderToMimeBd(email,bdMime);
    if (success != true) {
        System.out.println(mailman.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.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
    // an empty password string argument, but it is ignored.
    String password = "passwd";
    CkPrivateKey privKey = new CkPrivateKey();
    success = privKey.LoadAnyFormatFile("qa_data/pem/rsa_passwd.pem",password);
    if (success != true) {
        System.out.println(privKey.lastErrorText());
        return;
        }

    success = dkim.SetDkimPrivateKey(privKey);
    if (success != true) {
        System.out.println(dkim.lastErrorText());
        return;
        }

    // Add the DKIM-Signature header to the MIME in bdMime
    success = dkim.DkimSign(bdMime);
    if (success != true) {
        System.out.println(dkim.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")
    String strRecipients = "chilkat_software@yahoo.com, admin@chilkatsoft.com, admin@chilkat.io, chilkat.support@gmail.com";
    String strFrom = "support@chilkatsoft.com";

    success = mailman.SendMimeBd(strFrom,strRecipients,bdMime);
    if (success != true) {
        System.out.println(mailman.lastErrorText());
        return;
        }

    success = mailman.CloseSmtpConnection();
    if (success != true) {
        System.out.println("Connection to SMTP server not closed cleanly.");
        }

    System.out.println("DKIM Signed Mail Sent!");
  }
}