(.NET Core C#) 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.
Chilkat.MailMan mailman = 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).
string sshHostname = "sftp.example.com";
int sshPort = 22;

bool success = mailman.SshOpenTunnel(sshHostname,sshPort);
if (success != true) {
    Debug.WriteLine(mailman.LastErrorText);
    return;
}

// 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) {
    Debug.WriteLine(mailman.LastErrorText);
    return;
}

// 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
Chilkat.Email email = 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) {
    Debug.WriteLine(mailman.LastErrorText);
    return;
}

// 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!");