How to add a Screenshot as Attachment?

Hello,

i want to create a Email with a Screenshot as Attachment.

I create the screenshot like this:

 Application.CaptureScreenshot(attachmentFileName);

And i send the mail like that:

 //Mail Data
 private string fromAddress = "asd@gmail.com";
 private string toAddress = "asddd@outlook.com";
 private string subject = "Bug Report";
 private string smtpServer = "smtp.gmail.com";
 private int port = 587;
 private string credentialMail = "asd@gmail.com";
 private string credentialPass = "asd";
 private string attachmentFileName = "Screenshot.png";

 
 public void SendEMail()
 {
     MailMessage email = new MailMessage();
                 
     email.From = new MailAddress(fromAddress);
     email.To.Add(toAddress);
     email.Subject = subject;
     email.Body = "This is for testing SMTP mail from GMAIL";
         
     email.Attachments.Add (new Attachment (attachmentFileName));
         
     SmtpClient smtpServer = new SmtpClient("smtp.gmail.com");
     smtpServer.Port = port;
     smtpServer.Credentials = new System.Net.NetworkCredential(credentialMail, credentialPass) as ICredentialsByHost;
     smtpServer.EnableSsl = true;
     ServicePointManager.ServerCertificateValidationCallback = 
                     delegate(object s, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors) 
     { return true; };
     smtpServer.Send(email);
     Debug.Log("success");
 }

Anyone has a idea? Thanks!