Add filter to SMTP Client

Question

I am using the following code to send emails using SendGrid:

        string userName = ConfigurationManager.AppSettings["SendGridUser"];
        string passWord = ConfigurationManager.AppSettings["SendGridKey"];

        SmtpClient smtpClient = new SmtpClient("smtp.sendgrid.net", Convert.ToInt32(587));
        NetworkCredential credentials = new NetworkCredential(userName, passWord);
        smtpClient.Credentials = credentials;

        smtpClient.Send(mailMsg);

And now I need to add an additional filter setting and now sure how to add it. The filter that I need to include is to included the enabling of "bypass list management". How do I add that?

Answer 1

Twilio SendGrid developer evangelist here.

To send filters, such as "bypass list management", you should send them as a JSON string as part of the X-SMTPAPI header. You can read more about building an X-SMTPAPI header here.

An example X-SMTPAPI header that bypasses list management might look like:

{
  "filters": {
    "bypass_list_management": true
  }
}

You can add this to the headers of the mailMsg like so:

mailMsg.Headers.Add("X-SMTPAPI", jsonString);