(Go) GMail SMTP Send using Previously Obtained OAuth2 Access Token

Demonstrates how to send email using GMail and OAuth2 authentication. This example assumes an OAuth2 access token was previously obtained.

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    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // See Get GMail SMTP Access Token 
    // for sample code showing how to obtain a GMail SMTP access token for desktop apps.

    // In this example, our access token was previously saved to the following file which contains JSON like this:
    // 	{
    // 	 "access_token": "ya39.Ci-XA_C5bGgRDC3UaD-h0_NeL-DVIQnI2gHtBBBHkZzrwlARkwX6R3O0PCDEzRlfaQ",
    // 	 "token_type": "Bearer",
    // 	 "expires_in": 3600,
    // 	 "refresh_token": "1/r_2c_7jddspcdfesrrfKqfXtqo08D6Q-gUU0DsdfVMsx0c"
    // 	}
    // 
    json := chilkat.NewJsonObject()
    success := json.LoadFile("qa_data/tokens/_gmailSmtp.json")
    if success != true {
        fmt.Println("Failed to load GMail access token file.")
        json.DisposeJsonObject()
        return
    }

    accessToken := json.StringOf("access_token")

    mailman := chilkat.NewMailMan()

    // Set the properties for the GMail SMTP server:
    mailman.SetSmtpHost("smtp.gmail.com")
    mailman.SetSmtpPort(587)
    mailman.SetStartTLS(true)

    // The SMTP username should be the GMail address of the user's account that authorized your app to send email.
    mailman.SetSmtpUsername("chilkat.support@gmail.com")
    mailman.SetOAuth2AccessToken(*accessToken)

    // Create a new email object
    email := chilkat.NewEmail()

    email.SetSubject("This is a test")
    email.SetBody("This is a test")
    email.SetFrom("Chilkat <chilkat.support@gmail.com>")
    email.AddTo("Chilkat Admin","admin@chilkatsoft.com")
    // To add more recipients, call AddTo, AddCC, or AddBcc once per recipient.

    // Call SendEmail to connect to the SMTP server and send.
    // The connection (i.e. session) to the SMTP server remains
    // open so that subsequent SendEmail calls may use the
    // same connection.  
    success = mailman.SendEmail(email)
    if success != true {
        fmt.Println(mailman.LastErrorText())
        json.DisposeJsonObject()
        mailman.DisposeMailMan()
        email.DisposeEmail()
        return
    }

    // You may close the connection here.  If the connection is kept open, 
    // the next call to mailman.SendEmail will continue using the already-established connection
    // (and automatically re-connect if needed).
    success = mailman.CloseSmtpConnection()
    if success != true {
        fmt.Println("Connection to SMTP server not closed cleanly.")
    }

    fmt.Println("Email Sent via GMail with OAuth2 authentication.")

    json.DisposeJsonObject()
    mailman.DisposeMailMan()
    email.DisposeEmail()