diff --git a/Processor.ts b/Processor.ts
index ae7836b..5be7391 100644
--- a/Processor.ts
+++ b/Processor.ts
@@ -37,8 +37,9 @@ export class Processor {
                     break;
                 }
                 if (rule.condition.match(message_data)) {
-                    console.log(`rule ${rule} matches message ${message_data}, apply action ${rule.thread_action}`);
+                    console.log(`Rule ${rule} matches message ${message_data}, apply action ${rule.thread_action}`);
                     thread_data.thread_action.mergeFrom(rule.thread_action);
+                    console.log(`Thread action after merging: ${thread_data.thread_action}`)
                     let endThread = false;
                     switch (rule.thread_action.action_after_match) {
                         case ActionAfterMatchType.DONE:
@@ -168,22 +169,8 @@ export class Processor {
             expect(thread_data.thread_action.action_after_match).toBe(ActionAfterMatchType.DEFAULT);
             expect(thread_data.thread_action.important).toBe(BooleanActionType.DEFAULT);
             expect(thread_data.thread_action.label_names).toEqual(new Set(['abc', 'xyz']));
-            expect(thread_data.thread_action.move_to).toBe(InboxActionType.DEFAULT);
+            expect(thread_data.thread_action.move_to).toBe(InboxActionType.NOTHING);
             expect(thread_data.thread_action.read).toBe(BooleanActionType.DEFAULT);
         })
-        it('Throws error when message matches action but has no actions', () => {
-            expect(() => {
-                test_proc([
-                    {
-                        conditions: '(sender xyz@gmail.com)',
-                        stage: '5',
-                    },
-                ], [
-                    {
-                        getFrom: () => 'xyz@gmail.com',
-                        }
-                ])
-            }).toThrow();
-        })
     }
 }
diff --git a/Rule.ts b/Rule.ts
index a8b9555..63b79a5 100644
--- a/Rule.ts
+++ b/Rule.ts
@@ -70,7 +70,7 @@ export class Rule {
 
     private static parseInboxActionType(str: string): InboxActionType {
         if (str.length === 0) {
-            return InboxActionType.DEFAULT;
+            return InboxActionType.NOTHING;
         }
         const result = InboxActionType[str.toUpperCase() as keyof typeof InboxActionType];
         Utils.assert(result !== undefined, `Can't parse inbox action value ${str}.`);
diff --git a/ThreadAction.test.ts b/ThreadAction.test.ts
index 4375d0b..ae284a2 100644
--- a/ThreadAction.test.ts
+++ b/ThreadAction.test.ts
@@ -1,5 +1,43 @@
-import ThreadAction from './ThreadAction';
+import ThreadAction, {InboxActionType} from './ThreadAction';
+import Utils from './utils';
 
-describe('ThreadAction Tests', () => {
-  ThreadAction.testThreadActions(it, expect);
-})
+it('Adds parent labels', () => {
+  const labels = ['list/abc', 'bot/team1/test', 'bot/team1/alert', 'def'];
+  const action = new ThreadAction();
+  const expected = new Set(['list', 'list/abc', 'bot', 'bot/team1', 'bot/team1/test', 'bot/team1/alert', 'def'])
+
+  action.addLabels(labels);
+
+  Utils.assert(action.label_names.size === expected.size,
+    `Expected ${Array.from(expected).join(', ')},
+but got ${Array.from(action.label_names).join(', ')}`);
+
+  for (const label of expected) {
+    Utils.assert(action.label_names.has(label), `Expected label ${label}, but not present in action.`);
+  }
+});
+
+it('Does not add parent labels for empty list', () => {
+  const labels: string[] = [];
+  const action = new ThreadAction();
+
+  action.addLabels(labels);
+
+  Utils.assert(action.label_names.size === 0,
+    `Expected empty set, but got ${Array.from(action.label_names).join(', ')}`);
+});
+
+it('Correctly merges NOTHING actions', () => {
+  const thread_data_action = new ThreadAction();
+  const rule_action = new ThreadAction();
+  rule_action.move_to = InboxActionType.NOTHING;
+
+  Utils.assert(thread_data_action.move_to == InboxActionType.DEFAULT,
+    `move_to should be DEFAULT, but is ${thread_data_action.move_to}`);
+  thread_data_action.mergeFrom(rule_action);
+
+  Utils.assert(thread_data_action.move_to == InboxActionType.NOTHING,
+    `move_to should be NOTHING, but is ${thread_data_action.move_to}`);
+  Utils.assert(rule_action.toString() == '>NOTHING +L',
+    `rule_action should be '>NOTHING +L', but is ${rule_action}`);
+});
diff --git a/ThreadAction.ts b/ThreadAction.ts
index 3e1f0cc..a9449ec 100644
--- a/ThreadAction.ts
+++ b/ThreadAction.ts
@@ -16,7 +16,7 @@
 
 export enum BooleanActionType {DEFAULT, ENABLE, DISABLE}
 
-export enum InboxActionType {DEFAULT, INBOX, ARCHIVE, TRASH}
+export enum InboxActionType {DEFAULT, INBOX, ARCHIVE, TRASH, NOTHING}
 
 export enum ActionAfterMatchType {DEFAULT, DONE, FINISH_STAGE, NEXT_STAGE}
 
diff --git a/ThreadData.ts b/ThreadData.ts
index dc5297e..0d87a92 100644
--- a/ThreadData.ts
+++ b/ThreadData.ts
@@ -122,19 +122,19 @@ export class ThreadData {
     }
 
     validateActions() {
-        if (!this.thread_action.hasAnyAction()) {
+        if (!this.thread_action.hasAnyAction() && this.thread_action.move_to != InboxActionType.NOTHING) {
             const messages = this.raw.getMessages();
             const last_message = messages[messages.length - 1];
             const from = last_message.getFrom();
             const to = last_message.getTo();
-            throw `Thread "${this.raw.getFirstMessageSubject()}" from ${from} to ${to} has no action, does it match any rule?`;
+            throw `Thread "${this.raw.getFirstMessageSubject()}" from ${from} to ${to} has default action (${this.thread_action}), does it match any rule?`;
         }
     }
 
     static applyAllActions(session_data: SessionData, all_thread_data: ThreadData[]) {
         const label_action_map: { [key: string]: GoogleAppsScript.Gmail.GmailThread[] } = {};
         const moving_action_map = new Map<InboxActionType, GoogleAppsScript.Gmail.GmailThread[]>([
-            [InboxActionType.DEFAULT, []], [InboxActionType.INBOX, []], [InboxActionType.ARCHIVE, []], [InboxActionType.TRASH, []]
+            [InboxActionType.DEFAULT, []], [InboxActionType.INBOX, []], [InboxActionType.ARCHIVE, []], [InboxActionType.TRASH, []], [InboxActionType.NOTHING, []]
         ]);
         const important_action_map = new Map<BooleanActionType, GoogleAppsScript.Gmail.GmailThread[]>([
             [BooleanActionType.DEFAULT, []], [BooleanActionType.ENABLE, []], [BooleanActionType.DISABLE, []]