c# if statement && ||

currently I have code set up to send out an email once a url ping takes longer than 450ms. I want to change this so that it should only send the email once the ping was longer than 450ms more than once etc. So I don't end up recieving tons of emails. Thanks in advance. Please let me know if I need to include any more code.

 if ((int) response >= 450) {
   SendEmailPageloadFailed(site.Name, (int) response);
 }
 }
 entities.SaveChanges();
 return Json(status);
 }
 }