i am sending mail using SmtpClient and MailMessage , but the mail is going to spam and not in inbox

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ASP.NET

i am trying to send mail using SmtpClient and MailMessage object. Mail is being set succesfully but going to SPAM and not in inbox. Please suggest me what to add more here in my code.

here is my code..

public void SendMail(string from, string pwd ,string to)
   {
       try
       {
           SmtpClient smtp = new SmtpClient();
           smtp.Host = "smtp.gmail.com";
           smtp.Port = 587;
           smtp.EnableSsl = true;
           smtp.DeliveryMethod = SmtpDeliveryMethod.Network;
           smtp.Credentials = new System.Net.NetworkCredential(from, pwd);

           MailMessage Msg = new MailMessage(from, to, "Demo Mail", txtStfComments.Text);
           Msg.IsBodyHtml = false;
           smtp.Send(Msg);
       }
       catch (Exception ex)
       {
           throw ex;
       }
   }

i am calling this function on click event of a button.

Edit: removed sensitive information.