(VB.NET) SMTP SSH Tunneling (Port Forwarding)

Demonstrates how to setup an SSH tunnel for SMTP. This example connects to an SMTP sever via an SSH tunnel and sends an email.

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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 (SMTP) and receiving (POP3) email.
Dim mailman As New Chilkat.MailMan

' Connect to an SSH server and establish the SSH tunnel:

' The SSH hostname may be a hostname or an 
' IP address, such as "192.168.1.108".
' The port is typically 22 (the standard port for SSH).
Dim sshHostname As String = "sftp.example.com"
Dim sshPort As Integer = 22

Dim success As Boolean = mailman.SshOpenTunnel(sshHostname,sshPort)
If (success <> True) Then
    Debug.WriteLine(mailman.LastErrorText)
    Exit Sub
End If


' Authenticate with the SSH server via a login/password
' or with a public key.
' This example demonstrates SSH password authentication.
' Note: This is not authenticating with the SMTP server, it is
' for authenticating with the SSH server, which is separate.
success = mailman.SshAuthenticatePw("sshLogin","sshPassword")
If (success <> True) Then
    Debug.WriteLine(mailman.LastErrorText)
    Exit Sub
End If


' OK, the SSH tunnel is setup.  The mailman may
' be used exactly the same as usual, except all communications
' are now sent through the SSH tunnel.

' Set the SMTP server.
mailman.SmtpHost = "smtp.my-smtp-server.com"

' Set the SMTP login/password (if required)
mailman.SmtpUsername = "smtpLogin"
mailman.SmtpPassword = "smtpPassword"

' 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>"
success = email.AddTo("Chilkat Admin","admin@chilkatsoft.com")

' The call to SendEmail automatically connects to the SMTP
' server via the SSH tunnel (if not already connected).
' Because the SSH tunnel has been previously setup,
' this does not establish a direct connection with the SMTP
' server.  It directs the SSH server to establish the connection.

' After SendEmail completes, the connection (i.e. session) remains
' open so that subsequent SendEmail calls may use the
' same SSH tunnel.  
success = mailman.SendEmail(email)
If (success <> True) Then
    Debug.WriteLine(mailman.LastErrorText)
    Exit Sub
End If


' If you're curious, have a look at LastErrorText after
' a successful send.  You'll see detailed information that 
' confirms the SSH tunneling.
Debug.WriteLine(mailman.LastErrorText)

' Note: 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.  

Debug.WriteLine("Mail Sent!")