Open a Persistent SMTP Connection

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Demonstrates the Chilkat MailMan.OpenSmtpConnection method, which explicitly opens a connection to the SMTP server and authenticates if a username and password, OAuth2 token, or other applicable settings have been provided. This example opens the connection, notes where sending would occur, and closes it.

Background: By default, sending a single email opens a connection, sends, and closes it. When sending many messages, that per-message overhead adds up. Explicitly calling OpenSmtpConnection once, sending in a loop, then CloseSmtpConnection keeps a single authenticated session open for the whole batch — substantially faster and gentler on the server than reconnecting each time.

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bool success = false;

//  Demonstrates the MailMan.OpenSmtpConnection method, which explicitly opens a connection
//  to the SMTP server and authenticates if credentials (or an OAuth2 token) have been
//  provided.

Chilkat.MailMan mailman = new Chilkat.MailMan();

//  Configure the SMTP server connection.
mailman.SmtpHost = "smtp.example.com";
mailman.SmtpPort = 465;
mailman.SmtpSsl = true;
mailman.SmtpUsername = "user@example.com";
mailman.SmtpPassword = "myPassword";

//  Explicitly open (and authenticate) the SMTP connection.

success = mailman.OpenSmtpConnection();
if (success == false) {
    Debug.WriteLine(mailman.LastErrorText);
    return;
}

Debug.WriteLine("SMTP connection opened.");

//  ... send one or more emails here ...

//  Close the connection when done.
success = mailman.CloseSmtpConnection();
if (success == false) {
    Debug.WriteLine(mailman.LastErrorText);
    return;
}