(VB.NET) Send DKIM Signed Email

Demonstrates how to send DKIM signed email.

Chilkat .NET Downloads Chilkat .NET Framework Chilkat for .NET Core

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

Dim success As Boolean
Dim mailman As New Chilkat.MailMan
Dim dkim As New Chilkat.Dkim

' SMTP server settings...
mailman.SmtpHost = "SMTP_DOMAIN"
mailman.SmtpUsername = "SMTP_LOGIN"
mailman.SmtpPassword = "SMTP_PASSWORD"
mailman.SmtpPort = 465
mailman.SmtpSsl = True

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>"

' 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...
Dim bdMime As New Chilkat.BinData
success = mailman.RenderToMimeBd(email,bdMime)
If (success <> True) Then
    Debug.WriteLine(mailman.LastErrorText)
    Exit Sub
End If


' 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.
Dim password As String = "passwd"
Dim privKey As New Chilkat.PrivateKey
success = privKey.LoadAnyFormatFile("qa_data/pem/rsa_passwd.pem",password)
If (success <> True) Then
    Debug.WriteLine(privKey.LastErrorText)
    Exit Sub
End If


success = dkim.SetDkimPrivateKey(privKey)
If (success <> True) Then
    Debug.WriteLine(dkim.LastErrorText)
    Exit Sub
End If


' Add the DKIM-Signature header to the MIME in bdMime
success = dkim.DkimSign(bdMime)
If (success <> True) Then
    Debug.WriteLine(dkim.LastErrorText)
    Exit Sub
End If


' 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")
Dim strRecipients As String = "chilkat_software@yahoo.com, admin@chilkatsoft.com, admin@chilkat.io, chilkat.support@gmail.com"
Dim strFrom As String = "support@chilkatsoft.com"

success = mailman.SendMimeBd(strFrom,strRecipients,bdMime)
If (success <> True) Then
    Debug.WriteLine(mailman.LastErrorText)
    Exit Sub
End If


success = mailman.CloseSmtpConnection()
If (success <> True) Then
    Debug.WriteLine("Connection to SMTP server not closed cleanly.")
End If


Debug.WriteLine("DKIM Signed Mail Sent!")