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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'  The mailman object is used for sending (SMTP) and receiving (POP3) email.
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("Component unlock failed")
    Exit Sub
End If


'  Connect to an SSH server and establish the SSH tunnel:
Dim sshHostname As String
Dim sshPort As Long
Dim bSmtp As Boolean
'  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).
sshHostname = "www.my-ssh-server.com"
sshPort = 22
bSmtp = true
'  The 1st argument passed to SshTunnel indicates whether
'  a tunnel for SMTP or POP3 is being established.
success = mailman.SshTunnel(bSmtp,sshHostname,sshPort)
If (success <> true) Then
    MsgBox(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(bSmtp,"sshLogin","sshPassword")
If (success <> true) Then
    MsgBox(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.chilkatsoft.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>"
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
    MsgBox(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.
MsgBox(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.


MsgBox("Mail Sent!")