title: Attaching to sendgrid api not working when using sendgrid mail helper
body: <p>I have looked through the questions i can find on here about attaching a file to a sendgrid email but none seem to have the issue I am. </p>
  
  <p>My question is is this. How do you send an email with an attachment in sendgrid using the api?</p>
  
  <pre><code> dynamic sg = new SendGridAPIClient(apiKey);
          var from = new SendGrid.Helpers.Mail.Email("jkennedy@domain.com");
          var subject = "Hello World from the SendGrid C# Library!";
          var to = new SendGrid.Helpers.Mail.Email(toAddress);
          var content = new Content("multipart/form-data", "Textual content");
          var attachment = new Attachment {Filename = attachmentPath };
          var mail = new Mail(from, subject, to, content);
  
          var ret = mail.Get();
  
          mail.AddAttachment(attachment);
  
  
          dynamic response = await sg.client.mail.send.post(requestBody: ret);
  </code></pre>
  
  <p>If i put the mail.attachment after the get the mail sends but there is no attachment. If i put the addattachment line before the get i get a "bad request" message.</p>
  
  <p>I have yet to find an example of exactly how to do this.</p>
  
  <p>Also, the path to the file is c:\tblaccudatacounts.csv</p>