Send DKIM Signed Email

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

Note: Requires version 9.0.3 or greater (or v7.9.5 or greater of the Email ActiveX).

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'  This example uses the Chilkat MIME/DKIM component
'  for adding a DKIM signature, and the Chilkat Email
'  component for creating and sending the email.

'  The mailman object is used for sending and receiving email.
'  The mailman object is part of the Chilkat Email product.
Dim mailman As New Chilkat.MailMan()

'  Any string argument automatically begins the 30-day trial.
Dim success As Boolean
success = mailman.UnlockComponent("30-day trial")
If (success <> true) Then
    MsgBox(mailman.LastErrorText)
    Exit Sub
End If


'  The dkim object is used for creating the DKIM signature.
'  It belongs to the "Chilkat MIME" product.
Dim dkim As New Chilkat.Dkim()

success = dkim.UnlockComponent("Anything for 30-day trial")
If (success <> true) Then
    MsgBox(dkim.LastErrorText)
    Exit Sub
End If


'  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.
email.AddTo("Chilkat Software","chilkat_software@yahoo.com")
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 Byte
mimeData = mailman.RenderToMimeBytes(email)


'  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"
success = dkim.LoadDkimPkFile("myPrivateKey.pem",password)
If (success <> true) Then
    MsgBox(dkim.LastErrorText)
    Exit Sub
End If


'  Add the DKIM-Signature header and
'  returns the new MIME with DKIM-Signature added.
Dim dkimSignedMime() As Byte
dkimSignedMime = dkim.AddDkimSignature(mimeData)


'  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
    MsgBox(mailman.LastErrorText)
    Exit Sub
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
    MsgBox("Connection to SMTP server not closed cleanly.")
End If


MsgBox("DKIM Signed Mail Sent!")