(Xojo Plugin) Send DKIM Signed Email

Demonstrates how to create a simple email, add a DKIM signature, and send it.

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// 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.
Dim mailman As New Chilkat.MailMan

// The dkim object is used for creating the DKIM signature.
Dim dkim As New Chilkat.Dkim

// Set the SMTP server.
mailman.SmtpHost = "smtp.chilkatsoft.com"

// Set the SMTP login/password (if required)
mailman.SmtpUsername = "myUsername"
mailman.SmtpPassword = "myPassword"
// Set the SmtpPort if your SMTP server uses an alternative port (default = 25)
mailman.SmtpPort = 587

// Create a new email object
Dim email As New Chilkat.Email

email.Subject = "This is a test"
email.Body = "This is a test"
email.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.
Dim success As Boolean
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...
Dim mimeData As MemoryBlock
mimeData = mailman.RenderToMimeBytes(email)
If (mailman.LastMethodSuccess <> True) Then
    System.DebugLog(mailman.LastErrorText)
    Return
End If

// 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.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
// a password string argument, but it is ignored.
Dim password As String
password = "optionalPassword"
Dim privKey As New Chilkat.PrivateKey
success = privKey.LoadAnyFormatFile("myPrivateKey.pem",password)
If (success <> True) Then
    System.DebugLog(privKey.LastErrorText)
    Return
End If

success = dkim.SetDkimPrivateKey(privKey)
If (success <> True) Then
    System.DebugLog(dkim.LastErrorText)
    Return
End If

// Add the DKIM-Signature header and
// returns the new MIME with DKIM-Signature added.
Dim dkimSignedMime As MemoryBlock
dkimSignedMime = dkim.AddDkimSignature(mimeData)
If (dkim.LastMethodSuccess <> True) Then
    System.DebugLog(dkim.LastErrorText)
    Return
End If

// 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.  
Dim strFrom As String
strFrom = "support@chilkatsoft.com"
// To send to multiple email addresses, the strTo should be set to a comma-separated
// list of email addresses.
Dim strTo As String
strTo = "chilkat_software@yahoo.com, admin@chilkatsoft.com"
success = mailman.SendMimeBytes(strFrom,strTo,dkimSignedMime)
If (success <> True) Then
    System.DebugLog(mailman.LastErrorText)
    Return
End If

// 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 <> True) Then
    System.DebugLog("Connection to SMTP server not closed cleanly.")
End If

System.DebugLog("DKIM Signed Mail Sent!")