Revert "Prefer Date header over INTERNALDATE"

This reverts commit d1c2a688df.

app/src/main/java/eu/faircode/email/MessageHelper.java

@@ -772,16 +772,6 @@ public class MessageHelper {
     }
 
     long getReceived() throws MessagingException {
-        String date = imessage.getHeader("Date", null);
-        if (date != null) {
-            try {
-                Date received = new MailDateFormat().parse(date);
-                Log.i("Parsed received=" + received);
-                return received.getTime();
-            } catch (java.text.ParseException ignored) {
-            }
-        }
-
         Date received = imessage.getReceivedDate();
         if (received == null)
             received = imessage.getSentDate();