diff --git a/src/activitypub/actors.js b/src/activitypub/actors.js
index 40a3052e56..917efa4531 100644
--- a/src/activitypub/actors.js
+++ b/src/activitypub/actors.js
@@ -30,7 +30,7 @@ Actors.assert = async (ids, options = {}) => {
 
 	const actors = await Promise.all(ids.map(async (id) => {
 		try {
-			const actor = (typeof id === 'object' && id.hasOwnProperty('id')) ? await activitypub.get(0, id) : id;
+			const actor = (typeof id === 'object' && id.hasOwnProperty('id')) ? id : await activitypub.get(0, id);
 
 			// Follow counts
 			try {
diff --git a/src/activitypub/index.js b/src/activitypub/index.js
index 3df01c0ca6..6f276a4f06 100644
--- a/src/activitypub/index.js
+++ b/src/activitypub/index.js
@@ -26,6 +26,7 @@ ActivityPub.actors = require('./actors');
 ActivityPub.resolveInboxes = async (ids) => {
 	const inboxes = new Set();
 
+	await ActivityPub.actors.assert(ids);
 	await Promise.all(ids.map(async (id) => {
 		const { inbox, sharedInbox } = await user.getUserFields(id, ['inbox', 'sharedInbox']);
 		if (sharedInbox || inbox) {
@@ -190,7 +191,7 @@ ActivityPub.send = async (uid, targets, payload) => {
 	}
 
 	const userslug = await user.getUserField(uid, 'userslug');
-	const inboxes = await ActivityPub.resolveInboxes(uid, targets);
+	const inboxes = await ActivityPub.resolveInboxes(targets);
 
 	payload = {
 		'@context': 'https://www.w3.org/ns/activitystreams',
diff --git a/src/activitypub/mocks.js b/src/activitypub/mocks.js
index 74c577725d..374d4dc994 100644
--- a/src/activitypub/mocks.js
+++ b/src/activitypub/mocks.js
@@ -5,6 +5,7 @@ const mime = require('mime');
 
 const user = require('../user');
 const posts = require('../posts');
+const topics = require('../topics');
 
 const activitypub = module.parent.exports;
 const Mocks = module.exports;
@@ -53,7 +54,7 @@ Mocks.profile = async (actors) => {
 			followingCount,
 
 			inbox,
-			sharedInbox: endpoints.sharedInbox,
+			sharedInbox: endpoints ? endpoints.sharedInbox : null,
 		};
 
 		return payload;
@@ -174,13 +175,16 @@ Mocks.note = async (post) => {
 	const cc = [`${nconf.get('url')}/user/${userslug}/followers`];
 
 	let inReplyTo = null;
-	if (post.toPid) {
+	let name = null;
+	if (post.toPid) { // direct reply
 		inReplyTo = activitypub.helpers.isUri(post.toPid) ? post.toPid : `${nconf.get('url')}/post/${post.toPid}`;
 		const parentId = await posts.getPostField(post.toPid, 'uid');
 		to.unshift(activitypub.helpers.isUri(parentId) ? parentId : `${nconf.get('url')}/uid/${parentId}`);
-	} else if (!post.isMainPost) {
+	} else if (!post.isMainPost) { // reply to OP
 		inReplyTo = `${nconf.get('url')}/post/${post.topic.mainPid}`;
 		to.unshift(activitypub.helpers.isUri(post.topic.uid) ? post.topic.uid : `${nconf.get('url')}/uid/${post.topic.uid}`);
+	} else { // new topic
+		name = await topics.getTitleByPid(post.pid);
 	}
 
 	const object = {
@@ -194,6 +198,7 @@ Mocks.note = async (post) => {
 		attributedTo: `${nconf.get('url')}/uid/${post.user.uid}`,
 		sensitive: false, // todo
 		summary: null,
+		name,
 		content: post.content,
 		source: {
 			content: raw,
diff --git a/src/controllers/activitypub/index.js b/src/controllers/activitypub/index.js
index b718c55eb2..9f1c4f32a1 100644
--- a/src/controllers/activitypub/index.js
+++ b/src/controllers/activitypub/index.js
@@ -99,4 +99,6 @@ Controller.postInbox = async (req, res) => {
 			break;
 		}
 	}
+
+	res.sendStatus(200);
 };
diff --git a/src/topics/data.js b/src/topics/data.js
index 18e68dcb26..572a86f2be 100644
--- a/src/topics/data.js
+++ b/src/topics/data.js
@@ -100,6 +100,7 @@ function modifyTopic(topic, fields) {
 	if (validator.isUUID(String(topic.tid))) {
 		intFields.splice(intFields.indexOf('uid'), 1);
 		intFields.splice(intFields.indexOf('tid'), 1);
+		intFields.splice(intFields.indexOf('mainPid'), 1);
 	}
 	db.parseIntFields(topic, intFields, fields);
 
diff --git a/test/activitypub.js b/test/activitypub.js
index ac5d4574ce..ca28f3423e 100644
--- a/test/activitypub.js
+++ b/test/activitypub.js
@@ -11,6 +11,9 @@ const request = require('../src/request');
 
 const meta = require('../src/meta');
 const user = require('../src/user');
+const categories = require('../src/categories');
+const topics = require('../src/topics');
+const posts = require('../src/posts');
 const privileges = require('../src/privileges');
 const activitypub = require('../src/activitypub');
 
@@ -389,4 +392,57 @@ describe('ActivityPub integration', () => {
 			});
 		});
 	});
+
+	describe.only('Receipt of ActivityPub events to inboxes (federating IN)', () => {
+		describe('Create', () => {
+			describe('Note', () => {
+				let category;
+				let uid;
+				let note;
+				let topic;
+
+				before(async () => {
+					category = await categories.create({ name: 'test' });
+					const slug = slugify(utils.generateUUID().slice(0, 8));
+					uid = await user.create({ username: slug });
+
+					const { postData, topicData } = await topics.post({
+						uid,
+						cid: category.cid,
+						title: 'Lipsum title',
+						content: 'Lorem ipsum dolor sit amet',
+					});
+
+					const post = (await posts.getPostSummaryByPids([postData.pid], uid, { stripTags: false })).pop();
+					note = await activitypub.mocks.note(post);
+
+					await activitypub.send(uid, [`${nconf.get('url')}/uid/${uid}`], {
+						type: 'Create',
+						object: note,
+					});
+
+					const tid = await posts.getPostField(note.id, 'tid');
+					topic = await topics.getTopicData(tid);
+				});
+
+				it('should create a new topic if Note is at root-level or its parent has not been seen before', async () => {
+					const saved = await db.getObject(`post:${note.id}`);
+
+					assert(saved);
+					assert(topic);
+					assert.strictEqual(saved.uid, `${nconf.get('url')}/uid/${uid}`);
+					assert.strictEqual(saved.content, 'Lorem ipsum dolor sit amet');
+					assert(saved.tid);
+				});
+
+				it('should properly save the topic title in the topic hash', async () => {
+					assert.strictEqual(topic.title, 'Lipsum title');
+				});
+
+				it('should properly save the mainPid in the topic hash', async () => {
+					assert.strictEqual(topic.mainPid, note.id);
+				});
+			});
+		});
+	});
 });