Open a Persistent SMTP Connection

See more SMTP Examples

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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    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.

    mailman := chilkat.NewMailMan()

    //  Configure the SMTP server connection.
    mailman.SetSmtpHost("smtp.example.com")
    mailman.SetSmtpPort(465)
    mailman.SetSmtpSsl(true)
    mailman.SetSmtpUsername("user@example.com")
    mailman.SetSmtpPassword("myPassword")

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

    success = mailman.OpenSmtpConnection()
    if success == false {
        fmt.Println(mailman.LastErrorText())
        mailman.DisposeMailMan()
        return
    }

    fmt.Println("SMTP connection opened.")

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

    //  Close the connection when done.
    success = mailman.CloseSmtpConnection()
    if success == false {
        fmt.Println(mailman.LastErrorText())
        mailman.DisposeMailMan()
        return
    }


    mailman.DisposeMailMan()