diff --git a/backend/00-router.go b/backend/00-router.go
index acb8512..a6e16fa 100644
--- a/backend/00-router.go
+++ b/backend/00-router.go
@@ -73,7 +73,11 @@ func mailSendHandler(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, err.Error(), http.StatusBadRequest)
 		return
 	}
-	to := splitRecipients(r.FormValue("to"))
+	to, err := splitRecipients(r.FormValue("to"))
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
 	subject := strings.TrimSpace(r.FormValue("subject"))
 	body := r.FormValue("body")
 	if len(to) == 0 {
@@ -91,21 +95,27 @@ func mailSendHandler(w http.ResponseWriter, r *http.Request) {
 	fmt.Fprint(w, "gesendet")
 }
 
-func splitRecipients(value string) []string {
-	fields := strings.FieldsFunc(value, func(r rune) bool {
-		return r == ',' || r == ';' || r == '\n' || r == '\r' || r == '\t' || r == ' '
-	})
-	recipients := make([]string, 0, len(fields))
-	seen := make(map[string]bool, len(fields))
-	for _, field := range fields {
-		addr := strings.TrimSpace(field)
-		if addr == "" || seen[strings.ToLower(addr)] {
+func splitRecipients(value string) ([]string, error) {
+	normalized := strings.NewReplacer(";", ",", "\r\n", ",", "\n", ",", "\r", ",").Replace(strings.TrimSpace(value))
+	if normalized == "" {
+		return nil, nil
+	}
+	parsed, err := mail.ParseAddressList(normalized)
+	if err != nil {
+		return nil, fmt.Errorf("Ungueltiger Empfaenger: %s", err)
+	}
+	recipients := make([]string, 0, len(parsed))
+	seen := make(map[string]bool, len(parsed))
+	for _, address := range parsed {
+		addr := strings.TrimSpace(address.Address)
+		key := strings.ToLower(addr)
+		if addr == "" || seen[key] {
 			continue
 		}
 		recipients = append(recipients, addr)
-		seen[strings.ToLower(addr)] = true
+		seen[key] = true
 	}
-	return recipients
+	return recipients, nil
 }
 
 func homeHandler(w http.ResponseWriter, r *http.Request) {