Невозможно редактировать в редакторе только для чтения VS Code

public static bool SendMail(string strFrom, string strTo, string strSubject, string strMsg)
    {            
        try
        {                
            // Create the mail message
            MailMessage objMailMsg = new MailMessage(strFrom, strTo);

            objMailMsg.BodyEncoding = Encoding.UTF8;
            objMailMsg.Subject = strSubject;
            objMailMsg.Body = strMsg;
            Attachment at = new Attachment(Server.MapPath("~/Uploaded/txt.doc"));
            objMailMsg.Attachments.Add(at);
            objMailMsg.Priority = MailPriority.High;
            objMailMsg.IsBodyHtml = true;

            //prepare to send mail via SMTP transport
            SmtpClient objSMTPClient = new SmtpClient();
            objSMTPClient.DeliveryMethod = SmtpDeliveryMethod.PickupDirectoryFromIis;
            objSMTPClient.Send(objMailMsg);
            return true;                
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }  
  Ссылка