Auto retry search without keywords

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

@@ -509,11 +509,25 @@ public class BoundaryCallbackMessages extends PagedList.BoundaryCallback<TupleMe
                                             return search(true, browsable.keywords, protocol, state);
                                         } catch (Throwable ex) {
                                             EntityLog.log(context, ex.toString());
-                                            if (ex instanceof ProtocolException &&
-                                                    ex.getMessage() != null &&
-                                                    ex.getMessage().contains("full text search not supported")) {
+                                            if (ex instanceof ProtocolException && ex.getMessage() != null)
+                                                try {
+                                                    boolean retry = false;
+                                                    String remark = null;
+                                                    if (ex.getMessage().contains("full text search not supported")) {
+                                                        retry = true;
+                                                        criteria.in_message = false;
+                                                    } else if (ex.getMessage().contains("invalid search criteria")) {
+                                                        // invalid SEARCH command syntax, invalid search criteria syntax
+                                                        retry = true;
+                                                        criteria.in_keywords = false;
+                                                        remark = "Keyword search not supported?";
+                                                    }
+
+                                                    if (retry) {
                                                         String msg = context.getString(R.string.title_service_auth,
-                                                        account.host + ": " + getMessage(ex));
+                                                                account.host + ": " +
+                                                                        (remark == null ? "" : remark + " - ") +
+                                                                        getMessage(ex));
                                                         ApplicationEx.getMainHandler().post(new Runnable() {
                                                             @Override
                                                             public void run() {
@@ -521,7 +535,11 @@ public class BoundaryCallbackMessages extends PagedList.BoundaryCallback<TupleMe
                                                                     intf.onWarning(msg);
                                                             }
                                                         });
-                                                criteria.in_message = false;
+
+                                                        return search(true, browsable.keywords, protocol, state);
+                                                    }
+                                                } catch (Throwable exex) {
+                                                    Log.w(exex);
                                                 }
                                         }