Weiterleitung von Gast-Mails an Moderatoren bei moderierten Listen implementiert. Behebt Issue #1

Signed-off-by: Stephan Richter <s.richter@srsoftware.de>

src/main/java/de/srsoftware/widerhall/data/ListMember.java

@@ -322,6 +322,7 @@ public class ListMember {
      * @throws SQLException
      */
     public static ListMember load(MailingList list,User user) throws SQLException {
+        if (list == null || user == null) return null;
         var rs = Database
                 .open()
                 .select(TABLE_NAME)

src/main/java/de/srsoftware/widerhall/data/MailingList.java

@@ -432,30 +432,22 @@ public class MailingList implements MessageHandler, ProblemListener {
                 var senderEmail = internetAddress.getAddress();
 
                 var user = User.load(senderEmail);
-                if (user == null) { // no subscription
-                    if (this.isOpenForGuests()) {
-                        forward(message,subscribers());
-                    } else {
-                        retainMessage(message);
-                        sentRetentionNotification(senderEmail);
-
-                    }
-                    return;
-                }
-
                 var member = ListMember.load(this, user);
                 if (member == null || member.isAwaiting()) { // no subscription
                     if (this.isOpenForGuests()) {
                         forward(message, subscribers());
-                    } else {
+                    } else if (this.isOpenForSubscribers()){
                         retainMessage(message);
                         sentRetentionNotification(senderEmail);
+                    } else {
+                        // at this point, the message is from a non-member and the list
+                        // is only open to moderators. → forward to moderators
+                        forward(message, moderators());
                     }
                     return;
                 }
 
                 // at this point the member is at least a subscriber!
-
                 if (member.isModerator() || this.isOpenForSubscribers()) {
                     forward(message,subscribers());
                 } else {