change referrence from brandon.ad to bangmail.org

bang.go

@@ -181,7 +181,7 @@ func receiveEmailHandler(w http.ResponseWriter, r *http.Request) {
 	}
 	email.ID = fmt.Sprintf("%d", time.Now().UnixNano())
 	email.Timestamp = time.Now()
-	if email.Domain == "brandon.ad" {
+	if email.Domain == "bangmail.org" {
 		if err := saveEmail(email); err != nil {
 			http.Error(w, "Failed to save email", http.StatusInternalServerError)
 			return