diff --git a/apps/meteor/app/threads/server/functions.ts b/apps/meteor/app/threads/server/functions.ts
index b747a8d5d9555..7906f33ba77b0 100644
--- a/apps/meteor/app/threads/server/functions.ts
+++ b/apps/meteor/app/threads/server/functions.ts
@@ -1,6 +1,6 @@
-import type { IMessage } from '@rocket.chat/core-typings';
+import type { IMessage, IRoom } from '@rocket.chat/core-typings';
 import { isEditedMessage } from '@rocket.chat/core-typings';
-import { Messages, Subscriptions, ReadReceipts, NotificationQueue } from '@rocket.chat/models';
+import { Messages, Subscriptions, ReadReceipts, NotificationQueue, Rooms } from '@rocket.chat/models';
 
 import {
 	notifyOnSubscriptionChangedByRoomIdAndUserIds,
@@ -8,57 +8,90 @@ import {
 } from '../../lib/server/lib/notifyListener';
 import { getMentions, getUserIdsFromHighlights } from '../../lib/server/lib/notifyUsersOnMessage';
 
+const filterUsersInRoom = async ({ roomId, userIds, room }: { roomId: string; userIds: string[]; room: IRoom | null }) => {
+	if (!userIds.length || !room) {
+		return [];
+	}
+
+	if (room.t === 'd') {
+		return userIds.filter((userId) => room.uids?.includes(userId));
+	}
+
+	if (room.t === 'p' || room.t === 'c') {
+		const subscriptions = await Subscriptions.findByRoomIdAndUserIds(roomId, userIds, {
+			projection: { u: 1 },
+		}).toArray();
+
+		return subscriptions.map((sub) => sub.u._id);
+	}
+
+	return [];
+};
+
 export async function reply({ tmid }: { tmid?: string }, message: IMessage, parentMessage: IMessage, followers: string[]) {
 	if (!tmid || isEditedMessage(message)) {
 		return false;
 	}
 
 	const { rid, ts, u } = message;
+	const room = await Rooms.findOneById(rid);
 
 	const { toAll, toHere, mentionIds } = await getMentions(message);
 
-	const addToReplies = [
-		...new Set([
-			...followers,
-			...mentionIds,
-			...(Array.isArray(parentMessage.replies) && parentMessage.replies.length ? [u._id] : [parentMessage.u._id, u._id]),
-		]),
-	];
-
-	await Messages.updateRepliesByThreadId(tmid, addToReplies, ts);
-
 	const [highlightsUids, threadFollowers] = await Promise.all([
 		getUserIdsFromHighlights(rid, message),
 		Messages.getThreadFollowsByThreadId(tmid),
 	]);
 
-	const threadFollowersUids = threadFollowers?.filter((userId) => userId !== u._id && !mentionIds.includes(userId)) || [];
+	const [followersInRoom, mentionIdsInRoom, highlightsUidsInRoom, threadFollowersInRoom] = await Promise.all([
+		filterUsersInRoom({ roomId: rid, userIds: followers, room }),
+		filterUsersInRoom({ roomId: rid, userIds: mentionIds, room }),
+		filterUsersInRoom({ roomId: rid, userIds: highlightsUids, room }),
+		filterUsersInRoom({ roomId: rid, userIds: threadFollowers || [], room }),
+	]);
+
+	const baseReplyUsers = Array.isArray(parentMessage.replies) && parentMessage.replies.length ? [u._id] : [parentMessage.u._id, u._id];
+
+	const baseReplyUsersInRoom = await filterUsersInRoom({
+		roomId: rid,
+		userIds: baseReplyUsers,
+		room,
+	});
+
+	const addToReplies = [...new Set([...followersInRoom, ...mentionIdsInRoom, ...baseReplyUsersInRoom])];
+
+	await Messages.updateRepliesByThreadId(tmid, addToReplies, ts);
+
+	const threadFollowersUids = threadFollowersInRoom.filter((userId) => userId !== u._id && !mentionIdsInRoom.includes(userId));
 
-	// Notify everyone involved in the thread
 	const notifyOptions = toAll || toHere ? { groupMention: true } : {};
 
-	// Notify message mentioned users and highlights
-	const mentionedUsers = [...new Set([...mentionIds, ...highlightsUids])];
+	// Notify everyone involved in the thread
+	const mentionedUsers = [...new Set([...mentionIdsInRoom, ...highlightsUidsInRoom])];
 
-	const promises = [
+	const promises: Promise<unknown>[] = [
 		ReadReceipts.setAsThreadById(tmid),
 		Subscriptions.addUnreadThreadByRoomIdAndUserIds(rid, threadFollowersUids, tmid, notifyOptions),
 	];
 
 	if (mentionedUsers.length) {
-		promises.push(Subscriptions.addUnreadThreadByRoomIdAndUserIds(rid, mentionedUsers, tmid, { userMention: true }));
+		promises.push(
+			Subscriptions.addUnreadThreadByRoomIdAndUserIds(rid, mentionedUsers, tmid, {
+				userMention: true,
+			}),
+		);
 	}
 
-	if (highlightsUids.length) {
+	if (highlightsUidsInRoom.length) {
 		promises.push(
-			Subscriptions.setAlertForRoomIdAndUserIds(rid, highlightsUids),
-			Subscriptions.setOpenForRoomIdAndUserIds(rid, highlightsUids),
+			Subscriptions.setAlertForRoomIdAndUserIds(rid, highlightsUidsInRoom),
+			Subscriptions.setOpenForRoomIdAndUserIds(rid, highlightsUidsInRoom),
 		);
 	}
 
 	await Promise.allSettled(promises);
 
-	void notifyOnSubscriptionChangedByRoomIdAndUserIds(rid, [...threadFollowersUids, ...mentionedUsers, ...highlightsUids]);
+	void notifyOnSubscriptionChangedByRoomIdAndUserIds(rid, [...threadFollowersUids, ...mentionedUsers, ...highlightsUidsInRoom]);
 }
 
 export async function follow({ tmid, uid }: { tmid: string; uid: string }) {