(Swift 3,4,5...) Send DKIM Signed Email

Demonstrates how to send DKIM signed email.

Chilkat Downloads for the Swift Programming Language MAC OS X (Cocoa) Objective-C/Swift Libs iOS Objective-C/Swift Libs

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

    var success: Bool
    let mailman = CkoMailMan()!
    let dkim = CkoDkim()!

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

    let email = CkoEmail()!

    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.add(to: "Chilkat Software", emailAddress: "chilkat_software@yahoo.com")
    email.add(to: "Chilkat Admin", emailAddress: "admin@chilkatsoft.com")
    email.addCC("Chilkat Admin", emailAddress: "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...
    let bdMime = CkoBinData()!
    success = mailman.render(toMimeBd: email, renderedMime: bdMime)
    if success != true {
        print("\(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.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.
    var password: String? = "passwd"
    let privKey = CkoPrivateKey()!
    success = privKey.loadAnyFormatFile("qa_data/pem/rsa_passwd.pem", password: password)
    if success != true {
        print("\(privKey.lastErrorText!)")
        return
    }

    success = dkim.setDkimPrivateKey(privKey)
    if success != true {
        print("\(dkim.lastErrorText!)")
        return
    }

    // Add the DKIM-Signature header to the MIME in bdMime
    success = dkim.dkimSign(bdMime)
    if success != true {
        print("\(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")
    var strRecipients: String? = "chilkat_software@yahoo.com, admin@chilkatsoft.com, admin@chilkat.io, chilkat.support@gmail.com"
    var strFrom: String? = "support@chilkatsoft.com"

    success = mailman.sendMimeBd(strFrom, recipients: strRecipients, mimeData: bdMime)
    if success != true {
        print("\(mailman.lastErrorText!)")
        return
    }

    success = mailman.closeSmtpConnection()
    if success != true {
        print("Connection to SMTP server not closed cleanly.")
    }

    print("DKIM Signed Mail Sent!")

}