C++

Send DKIM Signed Email

See more DKIM / DomainKey Examples

Demonstrates how to send DKIM signed email. C++

#include <CkMailMan.h>
#include <CkDkim.h>
#include <CkEmail.h>
#include <CkBinData.h>
#include <CkPrivateKey.h>

void ChilkatSample(void)
    {
    bool success = false;

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

    CkMailMan mailman;
    CkDkim dkim;

    //  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;

    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;
    success = mailman.RenderToMimeBd(email,bdMime);
    if (success == false) {
        std::cout << mailman.lastErrorText() << "\r\n";
        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.
    const char *password = "passwd";
    CkPrivateKey privKey;
    success = privKey.LoadAnyFormatFile("qa_data/pem/rsa_passwd.pem",password);
    if (success == false) {
        std::cout << privKey.lastErrorText() << "\r\n";
        return;
    }

    success = dkim.SetDkimPrivateKey(privKey);
    if (success == false) {
        std::cout << dkim.lastErrorText() << "\r\n";
        return;
    }

    //  Add the DKIM-Signature header to the MIME in bdMime
    success = dkim.DkimSign(bdMime);
    if (success == false) {
        std::cout << dkim.lastErrorText() << "\r\n";
        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")
    const char *strRecipients = "chilkat_software@yahoo.com, admin@chilkatsoft.com, admin@chilkat.io, chilkat.support@gmail.com";
    const char *strFrom = "support@chilkatsoft.com";

    success = mailman.SendMimeBd(strFrom,strRecipients,bdMime);
    if (success == false) {
        std::cout << mailman.lastErrorText() << "\r\n";
        return;
    }

    success = mailman.CloseSmtpConnection();
    if (success != true) {
        std::cout << "Connection to SMTP server not closed cleanly." << "\r\n";
    }

    std::cout << "DKIM Signed Mail Sent!" << "\r\n";
    }