diff --git a/lib/Chat/AutoComplete/SearchPlugin.php b/lib/Chat/AutoComplete/SearchPlugin.php
index 1ca840db782..72c8efbb471 100644
--- a/lib/Chat/AutoComplete/SearchPlugin.php
+++ b/lib/Chat/AutoComplete/SearchPlugin.php
@@ -32,11 +32,14 @@
 use OCP\Collaboration\Collaborators\ISearchPlugin;
 use OCP\Collaboration\Collaborators\ISearchResult;
 use OCP\Collaboration\Collaborators\SearchResultType;
+use OCP\IGroup;
+use OCP\IGroupManager;
 use OCP\IL10N;
 use OCP\IUserManager;
 
 class SearchPlugin implements ISearchPlugin {
 	protected IUserManager $userManager;
+	protected IGroupManager $groupManager;
 	protected GuestManager $guestManager;
 	protected TalkSession $talkSession;
 	protected ParticipantService $participantService;
@@ -47,6 +50,7 @@ class SearchPlugin implements ISearchPlugin {
 	protected ?Room $room = null;
 
 	public function __construct(IUserManager $userManager,
+								IGroupManager $groupManager,
 								GuestManager $guestManager,
 								TalkSession $talkSession,
 								ParticipantService $participantService,
@@ -54,6 +58,7 @@ public function __construct(IUserManager $userManager,
 								?string $userId,
 								IL10N $l) {
 		$this->userManager = $userManager;
+		$this->groupManager = $groupManager;
 		$this->guestManager = $guestManager;
 		$this->talkSession = $talkSession;
 		$this->participantService = $participantService;
@@ -82,7 +87,7 @@ public function search($search, $limit, $offset, ISearchResult $searchResult) {
 			}
 		}
 
-		$userIds = $guestAttendees = [];
+		$userIds = $groupIds = $guestAttendees = [];
 		if ($this->room->getType() === Room::TYPE_ONE_TO_ONE) {
 			// Add potential leavers of one-to-one rooms again.
 			$participants = json_decode($this->room->getName(), true);
@@ -97,11 +102,14 @@ public function search($search, $limit, $offset, ISearchResult $searchResult) {
 					$guestAttendees[] = $attendee;
 				} elseif ($attendee->getActorType() === Attendee::ACTOR_USERS) {
 					$userIds[] = $attendee->getActorId();
+				} elseif ($attendee->getActorType() === Attendee::ACTOR_GROUPS) {
+					$groupIds[] = $attendee->getActorId();
 				}
 			}
 		}
 
 		$this->searchUsers($search, $userIds, $searchResult);
+		$this->searchGroups($search, $groupIds, $searchResult);
 		$this->searchGuests($search, $guestAttendees, $searchResult);
 
 		return false;
@@ -157,6 +165,51 @@ protected function searchUsers(string $search, array $userIds, ISearchResult $se
 		$searchResult->addResultSet($type, $matches, $exactMatches);
 	}
 
+	protected function searchGroups(string $search, array $groupIds, ISearchResult $searchResult): void {
+		$search = strtolower($search);
+
+		$type = new SearchResultType('groups');
+
+		$matches = $exactMatches = [];
+		foreach ($groupIds as $groupId) {
+			if ($searchResult->hasResult($type, $groupId)) {
+				continue;
+			}
+
+			if ($search === '') {
+				$matches[] = $this->createGroupResult($groupId);
+				continue;
+			}
+
+			if (strtolower($groupId) === $search) {
+				$exactMatches[] = $this->createGroupResult($groupId);
+				continue;
+			}
+
+			if (stripos($groupId, $search) !== false) {
+				$matches[] = $this->createGroupResult($groupId);
+				continue;
+			}
+
+			$group = $this->groupManager->get($groupId);
+			if (!$group instanceof IGroup) {
+				continue;
+			}
+
+			if (strtolower($group->getDisplayName()) === $search) {
+				$exactMatches[] = $this->createGroupResult($group->getGID(), $group->getDisplayName());
+				continue;
+			}
+
+			if (stripos($group->getDisplayName(), $search) !== false) {
+				$matches[] = $this->createGroupResult($group->getGID(), $group->getDisplayName());
+				continue;
+			}
+		}
+
+		$searchResult->addResultSet($type, $matches, $exactMatches);
+	}
+
 	/**
 	 * @param string $search
 	 * @param Attendee[] $attendees
@@ -218,6 +271,25 @@ protected function createResult(string $type, string $uid, string $name): array
 		];
 	}
 
+	protected function createGroupResult(string $groupId, string $name = ''): array {
+		if ($name === '') {
+			$group = $this->groupManager->get($groupId);
+			if ($group instanceof IGroup) {
+				$name = $group->getDisplayName();
+			} else {
+				$name = $groupId;
+			}
+		}
+
+		return [
+			'label' => $name,
+			'value' => [
+				'shareType' => 'group',
+				'shareWith' => 'group/' . $groupId,
+			],
+		];
+	}
+
 	protected function createGuestResult(string $actorId, string $name): array {
 		return [
 			'label' => $name,
diff --git a/lib/Chat/Notifier.php b/lib/Chat/Notifier.php
index 82067338ea6..4bbc4e53d45 100644
--- a/lib/Chat/Notifier.php
+++ b/lib/Chat/Notifier.php
@@ -36,6 +36,8 @@
 use OCP\AppFramework\Utility\ITimeFactory;
 use OCP\Comments\IComment;
 use OCP\IConfig;
+use OCP\IGroup;
+use OCP\IGroupManager;
 use OCP\IUserManager;
 use OCP\Notification\IManager as INotificationManager;
 use OCP\Notification\INotification;
@@ -50,6 +52,7 @@
 class Notifier {
 	private INotificationManager $notificationManager;
 	private IUserManager $userManager;
+	private IGroupManager $groupManager;
 	private ParticipantService $participantService;
 	private Manager $manager;
 	private IConfig $config;
@@ -58,6 +61,7 @@ class Notifier {
 
 	public function __construct(INotificationManager $notificationManager,
 								IUserManager $userManager,
+								IGroupManager $groupManager,
 								ParticipantService $participantService,
 								Manager $manager,
 								IConfig $config,
@@ -65,6 +69,7 @@ public function __construct(INotificationManager $notificationManager,
 								Util $util) {
 		$this->notificationManager = $notificationManager;
 		$this->userManager = $userManager;
+		$this->groupManager = $groupManager;
 		$this->participantService = $participantService;
 		$this->manager = $manager;
 		$this->config = $config;
@@ -84,9 +89,9 @@ public function __construct(INotificationManager $notificationManager,
 	 * @param Room $chat
 	 * @param IComment $comment
 	 * @param array[] $alreadyNotifiedUsers
-	 * @psalm-param array<int, array{id: string, type: string}> $alreadyNotifiedUsers
+	 * @psalm-param array<int, array{id: string, type: string, reason: string}> $alreadyNotifiedUsers
 	 * @return string[] Users that were mentioned
-	 * @psalm-return array<int, array{id: string, type: string, ?attendee: Attendee}>
+	 * @psalm-return array<int, array{id: string, type: string, reason: string, sourceId?: string, attendee?: Attendee}>
 	 */
 	public function notifyMentionedUsers(Room $chat, IComment $comment, array $alreadyNotifiedUsers, bool $silent): array {
 		$usersToNotify = $this->getUsersToNotify($chat, $comment, $alreadyNotifiedUsers);
@@ -98,13 +103,22 @@ public function notifyMentionedUsers(Room $chat, IComment $comment, array $alrea
 		$shouldFlush = false;
 		if (!$silent) {
 			$notification = $this->createNotification($chat, $comment, 'mention');
+			$parameters = $notification->getSubjectParameters();
 			$shouldFlush = $this->notificationManager->defer();
 		}
 
+
 		foreach ($usersToNotify as $mentionedUser) {
 			if ($this->shouldMentionedUserBeNotified($mentionedUser['id'], $comment, $chat, $mentionedUser['attendee'] ?? null)) {
 				if (!$silent) {
 					$notification->setUser($mentionedUser['id']);
+					if (isset($mentionedUser['reason'])) {
+						$notification->setSubject('mention_' . $mentionedUser['reason'], array_merge($parameters, [
+							'sourceId' => $mentionedUser['sourceId'] ?? null,
+						]));
+					} else {
+						$notification->setSubject('mention', $parameters);
+					}
 					$this->notificationManager->notify($notification);
 				}
 				$alreadyNotifiedUsers[] = $mentionedUser;
@@ -122,30 +136,31 @@ public function notifyMentionedUsers(Room $chat, IComment $comment, array $alrea
 	 * @param Room $chat
 	 * @param IComment $comment
 	 * @param array $alreadyNotifiedUsers
-	 * @psalm-param array<int, array{id: string, type: string}> $alreadyNotifiedUsers
+	 * @psalm-param array<int, array{id: string, type: string, reason?: string}> $alreadyNotifiedUsers
 	 * @return array
-	 * @psalm-return array<int, array{id: string, type: string, ?attendee: Attendee}>
+	 * @psalm-return array<int, array{id: string, type: string, reason?: string, sourceId?: string, attendee?: Attendee}>
 	 */
 	private function getUsersToNotify(Room $chat, IComment $comment, array $alreadyNotifiedUsers): array {
 		$usersToNotify = $this->getMentionedUsers($comment);
-		$usersToNotify = $this->removeAlreadyNotifiedUsers($usersToNotify, $alreadyNotifiedUsers);
+		$usersToNotify = $this->getMentionedGroupMembers($chat, $comment, $usersToNotify);
 		$usersToNotify = $this->addMentionAllToList($chat, $usersToNotify);
+		$usersToNotify = $this->removeAlreadyNotifiedUsers($usersToNotify, $alreadyNotifiedUsers);
 
 		return $usersToNotify;
 	}
 
 	/**
 	 * @param array $usersToNotify
-	 * @psalm-param array<int, array{id: string, type: string}> $usersToNotify
+	 * @psalm-param array<int, array{id: string, type: string, reason?: string, sourceId?: string, attendee?: Attendee}> $usersToNotify
 	 * @param array $alreadyNotifiedUsers
-	 * @psalm-param array<int, array{id: string, type: string}> $alreadyNotifiedUsers
+	 * @psalm-param array<int, array{id: string, type: string, reason?: string}> $alreadyNotifiedUsers
 	 * @return array
-	 * @psalm-return array<int, array{id: string, type: string}>
+	 * @psalm-return array<int, array{id: string, type: string, reason?: string, sourceId?: string, attendee?: Attendee}>
 	 */
 	private function removeAlreadyNotifiedUsers(array $usersToNotify, array $alreadyNotifiedUsers): array {
 		return array_filter($usersToNotify, static function (array $userToNotify) use ($alreadyNotifiedUsers): bool {
 			foreach ($alreadyNotifiedUsers as $alreadyNotified) {
-				if ($alreadyNotified === $userToNotify) {
+				if ($alreadyNotified['id'] === $userToNotify['id'] && $alreadyNotified['type'] === $userToNotify['type']) {
 					return false;
 				}
 			}
@@ -156,13 +171,13 @@ private function removeAlreadyNotifiedUsers(array $usersToNotify, array $already
 	/**
 	 * @param Room $chat
 	 * @param array $list
-	 * @psalm-param array<int, array{id: string, type: string}> $list
+	 * @psalm-param array<int, array{id: string, type: string, reason: string, sourceId?: string}> $list
 	 * @return array
-	 * @psalm-return array<int, array{id: string, type: string, ?attendee: Attendee}>
+	 * @psalm-return array<int, array{id: string, type: string, reason: string, sourceId?: string, attendee?: Attendee}>
 	 */
 	private function addMentionAllToList(Room $chat, array $list): array {
-		$usersToNotify = array_filter($list, static function (array $user): bool {
-			return $user['id'] !== 'all';
+		$usersToNotify = array_filter($list, static function (array $entry): bool {
+			return $entry['type'] !== Attendee::ACTOR_USERS || $entry['id'] !== 'all';
 		});
 
 		if (count($list) === count($usersToNotify)) {
@@ -182,6 +197,7 @@ private function addMentionAllToList(Room $chat, array $list): array {
 				'id' => $attendee->getActorId(),
 				'type' => $attendee->getActorType(),
 				'attendee' => $attendee,
+				'reason' => 'all',
 			];
 		}
 
@@ -202,7 +218,7 @@ private function addMentionAllToList(Room $chat, array $list): array {
 	 * @param IComment $replyTo
 	 * @param bool $silent
 	 * @return array[] Actor that was replied to
-	 * @psalm-return array<int, array{id: string, type: string}>
+	 * @psalm-return array<int, array{id: string, type: string, reason: string}>
 	 */
 	public function notifyReplyToAuthor(Room $chat, IComment $comment, IComment $replyTo, bool $silent): array {
 		if ($replyTo->getActorType() !== Attendee::ACTOR_USERS) {
@@ -224,6 +240,7 @@ public function notifyReplyToAuthor(Room $chat, IComment $comment, IComment $rep
 			[
 				'id' => $replyTo->getActorId(),
 				'type' => $replyTo->getActorType(),
+				'reason' => 'reply',
 			],
 		];
 	}
@@ -241,7 +258,7 @@ public function notifyReplyToAuthor(Room $chat, IComment $comment, IComment $rep
 	 * @param IComment $comment
 	 * @param array[] $alreadyNotifiedUsers
 	 * @param bool $silent
-	 * @psalm-param array<int, array{id: string, type: string, ?attendee: Attendee}> $alreadyNotifiedUsers
+	 * @psalm-param array<int, array{id: string, type: string, reason: string, sourceId?: string, attendee?: Attendee}> $alreadyNotifiedUsers
 	 */
 	public function notifyOtherParticipant(Room $chat, IComment $comment, array $alreadyNotifiedUsers, bool $silent): void {
 		if ($silent) {
@@ -260,7 +277,7 @@ public function notifyOtherParticipant(Room $chat, IComment $comment, array $alr
 			$this->notificationManager->notify($notification);
 		}
 
-		// Also notify default participants in one2one chats or when the admin default is "always"
+		// Also notify default participants in one-to-one chats or when the admin default is "always"
 		if ($this->getDefaultGroupNotification() === Participant::NOTIFY_ALWAYS || $chat->getType() === Room::TYPE_ONE_TO_ONE) {
 			$participants = $this->participantService->getParticipantsByNotificationLevel($chat, Participant::NOTIFY_DEFAULT);
 			foreach ($participants as $participant) {
@@ -346,7 +363,7 @@ public function removePendingNotificationsForRoom(Room $chat, bool $chatOnly = f
 	 * Removes all the pending mention notifications for the room
 	 *
 	 * @param Room $chat
-	 * @param string $userId
+	 * @param ?string $userId
 	 */
 	public function markMentionNotificationsRead(Room $chat, ?string $userId): void {
 		if ($userId === null || $userId === '') {
@@ -383,7 +400,7 @@ public function getMentionedUserIds(IComment $comment): array {
 	/**
 	 * @param IComment $comment
 	 * @return array[]
-	 * @psalm-return array<int, array{type: string, id: string}>
+	 * @psalm-return array<int, array{type: string, id: string, reason: string}>
 	 */
 	private function getMentionedUsers(IComment $comment): array {
 		$mentions = $comment->getMentions();
@@ -394,16 +411,75 @@ private function getMentionedUsers(IComment $comment): array {
 
 		$mentionedUsers = [];
 		foreach ($mentions as $mention) {
-			if ($mention['type'] === 'user') {
-				$mentionedUsers[] = [
-					'id' => $mention['id'],
-					'type' => 'users'
-				];
+			if ($mention['type'] !== 'user') {
+				continue;
 			}
+
+			$mentionedUsers[] = [
+				'id' => $mention['id'],
+				'type' => 'users',
+				'reason' => 'direct',
+			];
 		}
 		return $mentionedUsers;
 	}
 
+	/**
+	 * @param Room $chat
+	 * @param IComment $comment
+	 * @param array $list
+	 * @psalm-param array<int, array{id: string, type: string, reason: string}> $list
+	 * @return array[]
+	 * @psalm-return array<int, array{type: string, id: string, reason: string, sourceId?: string}>
+	 */
+	private function getMentionedGroupMembers(Room $chat, IComment $comment, array $list): array {
+		$mentions = $comment->getMentions();
+
+		if (empty($mentions)) {
+			return [];
+		}
+
+		$alreadyMentionedUserIds = array_filter(
+			array_map(static fn (array $entry) => $entry['type'] === Attendee::ACTOR_USERS ? $entry['id'] : null, $list),
+			static fn ($userId) => $userId !== null
+		);
+		$alreadyMentionedUserIds = array_flip($alreadyMentionedUserIds);
+
+		foreach ($mentions as $mention) {
+			if ($mention['type'] !== 'group') {
+				continue;
+			}
+
+			$group = $this->groupManager->get($mention['id']);
+			if (!$group instanceof IGroup) {
+				continue;
+			}
+
+			try {
+				$this->participantService->getParticipantByActor($chat, Attendee::ACTOR_GROUPS, $group->getGID());
+			} catch (ParticipantNotFoundException $e) {
+				continue;
+			}
+
+			$members = $group->getUsers();
+			foreach ($members as $member) {
+				if (isset($alreadyMentionedUserIds[$member->getUID()])) {
+					continue;
+				}
+
+				$list[] = [
+					'id' => $member->getUID(),
+					'type' => Attendee::ACTOR_USERS,
+					'reason' => 'group',
+					'sourceId' => $group->getGID(),
+				];
+				$alreadyMentionedUserIds[$member->getUID()] = true;
+			}
+		}
+
+		return $list;
+	}
+
 	/**
 	 * Creates a notification for the given chat message comment and mentioned
 	 * user ID.
@@ -510,7 +586,7 @@ protected function shouldMentionedUserBeNotified(string $userId, IComment $comme
 	 * @param Participant $participant
 	 * @param IComment $comment
 	 * @param array $alreadyNotifiedUsers
-	 * @psalm-param array<int, array{type: string, id: string}> $alreadyNotifiedUsers
+	 * @psalm-param array<int, array{type: string, id: string, reason: string, sourceId?: string, attendee?: Attendee}> $alreadyNotifiedUsers
 	 * @return bool
 	 */
 	protected function shouldParticipantBeNotified(Participant $participant, IComment $comment, array $alreadyNotifiedUsers): bool {
diff --git a/lib/Chat/Parser/UserMention.php b/lib/Chat/Parser/UserMention.php
index f767343abe9..44bd6376628 100644
--- a/lib/Chat/Parser/UserMention.php
+++ b/lib/Chat/Parser/UserMention.php
@@ -31,6 +31,8 @@
 use OCA\Talk\Room;
 use OCA\Talk\Service\ParticipantService;
 use OCP\Comments\ICommentsManager;
+use OCP\IGroup;
+use OCP\IGroupManager;
 use OCP\IL10N;
 use OCP\IUserManager;
 
@@ -45,17 +47,20 @@ class UserMention {
 	 */
 	protected ICommentsManager $commentsManager;
 	protected IUserManager $userManager;
+	protected IGroupManager $groupManager;
 	protected GuestManager $guestManager;
 	protected ParticipantService $participantService;
 	protected IL10N $l;
 
 	public function __construct(ICommentsManager $commentsManager,
 								IUserManager $userManager,
+								IGroupManager $groupManager,
 								GuestManager $guestManager,
 								ParticipantService $participantService,
 								IL10N $l) {
 		$this->commentsManager = $commentsManager;
 		$this->userManager = $userManager;
+		$this->groupManager = $groupManager;
 		$this->guestManager = $guestManager;
 		$this->participantService = $participantService;
 		$this->l = $l;
@@ -104,15 +109,22 @@ public function parseMessage(Message $chatMessage): void {
 			}
 			$mentionTypeCount[$mention['type']]++;
 
+			$search = $mention['id'];
+			if ($mention['type'] === 'group') {
+				$search = 'group/' . $mention['id'];
+			}
+
 			// To keep a limited character set in parameter IDs ([a-zA-Z0-9-])
 			// the mention parameter ID does not include the mention ID (which
 			// could contain characters like '@' for user IDs) but a one-based
 			// index of the mentions of that type.
 			$mentionParameterId = 'mention-' . $mention['type'] . $mentionTypeCount[$mention['type']];
 
-			$message = str_replace('@"' . $mention['id'] . '"', '{' . $mentionParameterId . '}', $message);
-			if (strpos($mention['id'], ' ') === false && strpos($mention['id'], 'guest/') !== 0) {
-				$message = str_replace('@' . $mention['id'], '{' . $mentionParameterId . '}', $message);
+			$message = str_replace('@"' . $search . '"', '{' . $mentionParameterId . '}', $message);
+			if (strpos($search, ' ') === false
+				&& strpos($search, 'guest/') !== 0
+				&& strpos($search, 'group/') !== 0) {
+				$message = str_replace('@' . $search, '{' . $mentionParameterId . '}', $message);
 			}
 
 			if ($mention['type'] === 'call') {
@@ -140,6 +152,19 @@ public function parseMessage(Message $chatMessage): void {
 					'id' => $mention['id'],
 					'name' => $displayName,
 				];
+			} elseif ($mention['type'] === 'group') {
+				$group = $this->groupManager->get($mention['id']);
+				if ($group instanceof IGroup) {
+					$displayName = $group->getDisplayName();
+				} else {
+					$displayName = $mention['id'];
+				}
+
+				$messageParameters[$mentionParameterId] = [
+					'type' => 'user-group',
+					'id' => $mention['id'],
+					'name' => $displayName,
+				];
 			} else {
 				try {
 					$displayName = $this->commentsManager->resolveDisplayName($mention['type'], $mention['id']);
diff --git a/lib/Notification/Notifier.php b/lib/Notification/Notifier.php
index 740c4a9e8b1..f59cfb143c5 100644
--- a/lib/Notification/Notifier.php
+++ b/lib/Notification/Notifier.php
@@ -43,6 +43,7 @@
 use OCP\Comments\NotFoundException;
 use OCP\Files\IRootFolder;
 use OCP\HintException;
+use OCP\IGroupManager;
 use OCP\IL10N;
 use OCP\IURLGenerator;
 use OCP\IUser;
@@ -63,6 +64,7 @@ class Notifier implements INotifier {
 	protected IURLGenerator $url;
 	protected Config $config;
 	protected IUserManager $userManager;
+	protected IGroupManager $groupManager;
 	protected GuestManager $guestManager;
 	private IShareManager $shareManager;
 	protected Manager $manager;
@@ -85,6 +87,7 @@ public function __construct(IFactory $lFactory,
 								IURLGenerator $url,
 								Config $config,
 								IUserManager $userManager,
+								IGroupManager $groupManager,
 								GuestManager $guestManager,
 								IShareManager $shareManager,
 								Manager $manager,
@@ -101,6 +104,7 @@ public function __construct(IFactory $lFactory,
 		$this->url = $url;
 		$this->config = $config;
 		$this->userManager = $userManager;
+		$this->groupManager = $groupManager;
 		$this->guestManager = $guestManager;
 		$this->shareManager = $shareManager;
 		$this->manager = $manager;
@@ -277,7 +281,7 @@ public function prepare(INotification $notification, string $languageCode): INot
 			}
 			return $this->parseCall($notification, $room, $l);
 		}
-		if ($subject === 'reply' || $subject === 'mention' || $subject === 'chat' || $subject === 'reaction') {
+		if ($subject === 'reply' || $subject === 'mention' || $subject === 'mention_direct' || $subject === 'mention_group' || $subject === 'mention_all' || $subject === 'chat' || $subject === 'reaction') {
 			if ($room->getLobbyState() !== Webinary::LOBBY_NONE &&
 				$participant instanceof Participant &&
 				!($participant->getPermissions() & Attendee::PERMISSIONS_LOBBY_IGNORE)) {
@@ -609,15 +613,67 @@ protected function parseChatMessage(INotification $notification, Room $room, Par
 		} elseif ($room->getType() === Room::TYPE_ONE_TO_ONE || $room->getType() === Room::TYPE_ONE_TO_ONE_FORMER) {
 			$subject = $l->t('{user} mentioned you in a private conversation');
 		} elseif ($richSubjectUser) {
-			$subject = $l->t('{user} mentioned you in conversation {call}');
+			if ($notification->getSubject() === 'mention_group') {
+				$groupName = $this->groupManager->getDisplayName($subjectParameters['sourceId']) ?? $subjectParameters['sourceId'];
+				$richSubjectParameters['group'] = [
+					'type' => 'user-group',
+					'id' => $subjectParameters['sourceId'],
+					'name' => $groupName,
+				];
+
+				$subject = $l->t('{user} mentioned group {group} in conversation {call}');
+			} elseif ($notification->getSubject() === 'mention_all') {
+				$subject = $l->t('{user} mentioned everyone in conversation {call}');
+			} else {
+				$subject = $l->t('{user} mentioned you in conversation {call}');
+			}
 		} elseif (!$isGuest) {
-			$subject = $l->t('A deleted user mentioned you in conversation {call}');
+			if ($notification->getSubject() === 'mention_group') {
+				$groupName = $this->groupManager->getDisplayName($subjectParameters['sourceId']) ?? $subjectParameters['sourceId'];
+				$richSubjectParameters['group'] = [
+					'type' => 'user-group',
+					'id' => $subjectParameters['sourceId'],
+					'name' => $groupName,
+				];
+
+				$subject = $l->t('A deleted user mentioned group {group} in conversation {call}');
+			} elseif ($notification->getSubject() === 'mention_all') {
+				$subject = $l->t('A deleted user mentioned everyone in conversation {call}');
+			} else {
+				$subject = $l->t('A deleted user mentioned you in conversation {call}');
+			}
 		} else {
 			try {
 				$richSubjectParameters['guest'] = $this->getGuestParameter($room, $comment->getActorId());
-				$subject = $l->t('{guest} (guest) mentioned you in conversation {call}');
+				if ($notification->getSubject() === 'mention_group') {
+					$groupName = $this->groupManager->getDisplayName($subjectParameters['sourceId']) ?? $subjectParameters['sourceId'];
+					$richSubjectParameters['group'] = [
+						'type' => 'user-group',
+						'id' => $subjectParameters['sourceId'],
+						'name' => $groupName,
+					];
+
+					$subject = $l->t('{guest} (guest) mentioned group {group} in conversation {call}');
+				} elseif ($notification->getSubject() === 'mention_all') {
+					$subject = $l->t('{guest} (guest) mentioned everyone in conversation {call}');
+				} else {
+					$subject = $l->t('{guest} (guest) mentioned you in conversation {call}');
+				}
 			} catch (ParticipantNotFoundException $e) {
-				$subject = $l->t('A guest mentioned you in conversation {call}');
+				if ($notification->getSubject() === 'mention_group') {
+					$groupName = $this->groupManager->getDisplayName($subjectParameters['sourceId']) ?? $subjectParameters['sourceId'];
+					$richSubjectParameters['group'] = [
+						'type' => 'user-group',
+						'id' => $subjectParameters['sourceId'],
+						'name' => $groupName,
+					];
+
+					$subject = $l->t('A guest mentioned group {group} in conversation {call}');
+				} elseif ($notification->getSubject() === 'mention_all') {
+					$subject = $l->t('A guest mentioned everyone in conversation {call}');
+				} else {
+					$subject = $l->t('A guest mentioned you in conversation {call}');
+				}
 			}
 		}
 		$notification = $this->addActionButton($notification, $l->t('View chat'), false);
diff --git a/src/components/MessagesList/MessagesGroup/Message/Message.vue b/src/components/MessagesList/MessagesGroup/Message/Message.vue
index b789d298805..b2cac3332fd 100644
--- a/src/components/MessagesList/MessagesGroup/Message/Message.vue
+++ b/src/components/MessagesList/MessagesGroup/Message/Message.vue
@@ -518,7 +518,7 @@ export default {
 			Object.keys(this.messageParameters).forEach(function(p) {
 				const type = this.messageParameters[p].type
 				const mimetype = this.messageParameters[p].mimetype
-				if (type === 'user' || type === 'call' || type === 'guest') {
+				if (type === 'user' || type === 'call' || type === 'guest' || type === 'group') {
 					richParameters[p] = {
 						component: Mention,
 						props: this.messageParameters[p],
diff --git a/src/components/MessagesList/MessagesGroup/Message/MessagePart/Mention.vue b/src/components/MessagesList/MessagesGroup/Message/MessagePart/Mention.vue
index a133bd62916..4bffda11c12 100644
--- a/src/components/MessagesList/MessagesGroup/Message/MessagePart/Mention.vue
+++ b/src/components/MessagesList/MessagesGroup/Message/MessagePart/Mention.vue
@@ -25,6 +25,9 @@
 			:display-name="name"
 			:avatar-image="'icon-group-forced-white'"
 			:primary="true" />
+		<NcUserBubble v-else-if="isGroupMention"
+			:display-name="name"
+			:avatar-image="'icon-group-forced-white'" />
 		<NcUserBubble v-else-if="isMentionToGuest"
 			:display-name="name"
 			:avatar-image="'icon-user-forced-white'"
@@ -66,6 +69,9 @@ export default {
 		isMentionToAll() {
 			return this.type === 'call'
 		},
+		isGroupMention() {
+			return this.type === 'group'
+		},
 		isMentionToGuest() {
 			return this.type === 'guest'
 		},
diff --git a/src/components/NewMessageForm/NewMessageForm.vue b/src/components/NewMessageForm/NewMessageForm.vue
index fcc453527a6..a034b3ea70c 100644
--- a/src/components/NewMessageForm/NewMessageForm.vue
+++ b/src/components/NewMessageForm/NewMessageForm.vue
@@ -872,23 +872,28 @@ export default {
 				// Set icon for candidate mentions that are not for users.
 				if (possibleMention.source === 'calls') {
 					possibleMention.icon = 'icon-group-forced-white'
+					possibleMention.subline = t('spreed', 'Everyone')
+				} else if (possibleMention.source === 'groups') {
+					possibleMention.icon = 'icon-group-forced-white'
+					possibleMention.subline = t('spreed', 'Group')
 				} else if (possibleMention.source === 'guests') {
 					possibleMention.icon = 'icon-user-forced-white'
+					possibleMention.subline = t('spreed', 'Guest')
 				} else {
 					// The avatar is automatically shown for users, but an icon
 					// is nevertheless required as fallback.
 					possibleMention.icon = 'icon-user-forced-white'
-				}
 
-				// Convert status properties to an object.
-				if (possibleMention.status) {
-					const status = {
-						status: possibleMention.status,
-						icon: possibleMention.statusIcon,
+					// Convert status properties to an object.
+					if (possibleMention.status) {
+						possibleMention.status = {
+							status: possibleMention.status,
+							icon: possibleMention.statusIcon,
+						}
+						possibleMention.subline = possibleMention.statusMessage
 					}
-					possibleMention.status = status
-					possibleMention.subline = possibleMention.statusMessage
 				}
+
 				// Caching the user id data for each possible mention
 				this.userData[possibleMention.id] = possibleMention
 			})
diff --git a/tests/integration/features/bootstrap/FeatureContext.php b/tests/integration/features/bootstrap/FeatureContext.php
index 5f6f014c6d6..74fd1531b9f 100644
--- a/tests/integration/features/bootstrap/FeatureContext.php
+++ b/tests/integration/features/bootstrap/FeatureContext.php
@@ -1638,7 +1638,7 @@ public function userSeesPeersInCall(string $user, int $numPeers, string $identif
 	}
 
 	/**
-	 * @Then /^user "([^"]*)" (silent sends|sends) message "([^"]*)" to room "([^"]*)" with (\d+)(?: \((v1)\))?$/
+	 * @Then /^user "([^"]*)" (silent sends|sends) message ("[^"]*"|'[^']*') to room "([^"]*)" with (\d+)(?: \((v1)\))?$/
 	 *
 	 * @param string $user
 	 * @param string $sendingMode
@@ -1648,6 +1648,7 @@ public function userSeesPeersInCall(string $user, int $numPeers, string $identif
 	 * @param string $apiVersion
 	 */
 	public function userSendsMessageToRoom(string $user, string $sendingMode, string $message, string $identifier, string $statusCode, string $apiVersion = 'v1') {
+		$message = substr($message, 1, -1);
 		if ($sendingMode === 'silent sends') {
 			$body = new TableNode([['message', $message], ['silent', true]]);
 		} else {
@@ -1696,6 +1697,7 @@ public function userSharesRichObjectToRoom($user, $type, $id, $metaData, $identi
 		$response = $this->getDataFromResponse($this->response);
 		if (isset($response['id'])) {
 			self::$textToMessageId['shared::' . $type . '::' . $id] = $response['id'];
+			self::$messageIdToText[$response['id']] = 'shared::' . $type . '::' . $id;
 		}
 	}
 
@@ -2026,13 +2028,14 @@ public function userSendsMessageWithReferenceIdToRoom($user, $message, $referenc
 		$response = $this->getDataFromResponse($this->response);
 		if (isset($response['id'])) {
 			self::$textToMessageId[$message] = $response['id'];
+			self::$messageIdToText[$response['id']] = $message;
 		}
 
 		Assert::assertStringStartsWith($response['referenceId'], $referenceId);
 	}
 
 	/**
-	 * @Then /^user "([^"]*)" sends reply "([^"]*)" on message "([^"]*)" to room "([^"]*)" with (\d+)(?: \((v1)\))?$/
+	 * @Then /^user "([^"]*)" sends reply ("[^"]*"|'[^']*') on message ("[^"]*"|'[^']*') to room "([^"]*)" with (\d+)(?: \((v1)\))?$/
 	 *
 	 * @param string $user
 	 * @param string $reply
@@ -2042,6 +2045,8 @@ public function userSendsMessageWithReferenceIdToRoom($user, $message, $referenc
 	 * @param string $apiVersion
 	 */
 	public function userSendsReplyToRoom($user, $reply, $message, $identifier, $statusCode, $apiVersion = 'v1') {
+		$reply = substr($reply, 1, -1);
+		$message = substr($message, 1, -1);
 		$replyTo = self::$textToMessageId[$message];
 
 		$this->setCurrentUser($user);
@@ -2055,6 +2060,7 @@ public function userSendsReplyToRoom($user, $reply, $message, $identifier, $stat
 		$response = $this->getDataFromResponse($this->response);
 		if (isset($response['id'])) {
 			self::$textToMessageId[$reply] = $response['id'];
+			self::$messageIdToText[$response['id']] = $reply;
 		}
 	}
 
@@ -2196,6 +2202,7 @@ protected function compareDataResponse(TableNode $formData = null) {
 			self::$textToMessageId[$message['message']] = $message['id'];
 			if ($message['message'] === '{file}' && isset($message['messageParameters']['file']['name'])) {
 				self::$textToMessageId['shared::file::' . $message['messageParameters']['file']['name']] = $message['id'];
+				self::$messageIdToText[$message['id']] = 'shared::file::' . $message['messageParameters']['file']['name'];
 			}
 		}
 
@@ -2308,6 +2315,7 @@ public function userSeesTheFollowingSystemMessagesInRoom($user, $identifier, $st
 			// Include the received system messages in the list of messages used
 			// for replies.
 			self::$textToMessageId[$systemMessage['systemMessage']] = $systemMessage['id'];
+			self::$messageIdToText[$systemMessage['id']] = $systemMessage['systemMessage'];
 		}
 
 		if ($formData === null) {
diff --git a/tests/integration/features/chat/notifications.feature b/tests/integration/features/chat/notifications.feature
index 5dfa5d9ea50..527f6201d68 100644
--- a/tests/integration/features/chat/notifications.feature
+++ b/tests/integration/features/chat/notifications.feature
@@ -3,6 +3,8 @@ Feature: chat/notifications
   Background:
     Given user "participant1" exists
     Given user "participant2" exists
+    And group "attendees1" exists
+    And user "participant2" is member of group "attendees1"
 
   Scenario: Normal message when recipient is online in the one-to-one
     When user "participant1" creates room "one-to-one room" (v4)
@@ -235,8 +237,8 @@ Feature: chat/notifications
     Given user "participant2" joins room "room" with 200 (v4)
     When user "participant1" sends message "Hi @all bye" to room "room" with 201
     Then user "participant2" has the following notifications
-      | app    | object_type | object_id        | subject                                                     |
-      | spreed | chat        | room/Hi @all bye | participant1-displayname mentioned you in conversation room |
+      | app    | object_type | object_id        | subject                                                          |
+      | spreed | chat        | room/Hi @all bye | participant1-displayname mentioned everyone in conversation room |
 
   Scenario: At-all when recipient is offline in the group room
     When user "participant1" creates room "room" (v4)
@@ -248,8 +250,8 @@ Feature: chat/notifications
     Given user "participant2" leaves room "room" with 200 (v4)
     When user "participant1" sends message "Hi @all bye" to room "room" with 201
     Then user "participant2" has the following notifications
-      | app    | object_type | object_id        | subject                                                     |
-      | spreed | chat        | room/Hi @all bye | participant1-displayname mentioned you in conversation room |
+      | app    | object_type | object_id        | subject                                                          |
+      | spreed | chat        | room/Hi @all bye | participant1-displayname mentioned everyone in conversation room |
 
   Scenario: Silent at-all when recipient is offline in the group room
     When user "participant1" creates room "room" (v4)
@@ -276,6 +278,84 @@ Feature: chat/notifications
     Then user "participant2" has the following notifications
       | app | object_type | object_id | subject |
 
+  Scenario: Group-mention when recipient is online in the group room
+    When user "participant1" creates room "room" (v4)
+      | roomType | 2 |
+      | roomName | room |
+    And user "participant1" adds user "participant2" to room "room" with 200 (v4)
+    And user "participant1" adds group "attendees1" to room "room" with 200 (v4)
+    Given user "participant2" joins room "room" with 200 (v4)
+    When user "participant1" sends message 'Hi @"group/attendees1" bye' to room "room" with 201
+    Then user "participant2" has the following notifications
+      | app    | object_type | object_id        | subject                                                     |
+      | spreed | chat        | room/Hi @"group/attendees1" bye | participant1-displayname mentioned group attendees1 in conversation room |
+
+  Scenario: Group-mention when group is not a member of the room
+    When user "participant1" creates room "room" (v4)
+      | roomType | 2 |
+      | roomName | room |
+    And user "participant1" adds user "participant2" to room "room" with 200 (v4)
+    Given user "participant2" joins room "room" with 200 (v4)
+    When user "participant1" sends message 'Hi @"group/attendees1" bye' to room "room" with 201
+    Then user "participant2" has the following notifications
+      | app | object_type | object_id | subject |
+
+  Scenario: Group-mention when recipient is offline in the group room
+    When user "participant1" creates room "room" (v4)
+      | roomType | 2 |
+      | roomName | room |
+    And user "participant1" adds user "participant2" to room "room" with 200 (v4)
+    And user "participant1" adds group "attendees1" to room "room" with 200 (v4)
+    # Join and leave to clear the invite notification
+    Given user "participant2" joins room "room" with 200 (v4)
+    Given user "participant2" leaves room "room" with 200 (v4)
+    When user "participant1" sends message 'Hi @"group/attendees1" bye' to room "room" with 201
+    Then user "participant2" has the following notifications
+      | app    | object_type | object_id        | subject                                                     |
+      | spreed | chat        | room/Hi @"group/attendees1" bye | participant1-displayname mentioned group attendees1 in conversation room |
+
+  Scenario: Silent group-mention when recipient is offline in the group room
+    When user "participant1" creates room "room" (v4)
+      | roomType | 2 |
+      | roomName | room |
+    And user "participant1" adds user "participant2" to room "room" with 200 (v4)
+    And user "participant1" adds group "attendees1" to room "room" with 200 (v4)
+    # Join and leave to clear the invite notification
+    Given user "participant2" joins room "room" with 200 (v4)
+    Given user "participant2" leaves room "room" with 200 (v4)
+    When user "participant1" silent sends message 'Hi @"group/attendees1" bye' to room "room" with 201
+    Then user "participant2" has the following notifications
+      | app | object_type | object_id | subject |
+
+  Scenario: Group-mention when recipient with disabled notifications in the group room
+    When user "participant1" creates room "room" (v4)
+      | roomType | 2 |
+      | roomName | room |
+    And user "participant1" adds user "participant2" to room "room" with 200 (v4)
+    And user "participant1" adds group "attendees1" to room "room" with 200 (v4)
+    # Join and leave to clear the invite notification
+    Given user "participant2" joins room "room" with 200 (v4)
+    Given user "participant2" leaves room "room" with 200 (v4)
+    And user "participant2" sets notifications to disabled for room "room" (v4)
+    When user "participant1" sends message 'Hi @"group/attendees1" bye' to room "room" with 201
+    Then user "participant2" has the following notifications
+      | app | object_type | object_id | subject |
+
+  Scenario: Replying with all mention types only gives a reply notification
+    When user "participant1" creates room "room" (v4)
+      | roomType | 2 |
+      | roomName | room |
+    And user "participant1" adds user "participant2" to room "room" with 200 (v4)
+    And user "participant1" adds group "attendees1" to room "room" with 200 (v4)
+    # Join and leave to clear the invite notification
+    Given user "participant2" joins room "room" with 200 (v4)
+    Given user "participant2" leaves room "room" with 200 (v4)
+    When user "participant2" sends message "Hi part 1" to room "room" with 201
+    When user "participant1" sends reply 'Hi @all @participant2 @"group/attendees1" bye' on message "Hi part 1" to room "room" with 201
+    Then user "participant2" has the following notifications
+      | app    | object_type | object_id        | subject                                                     |
+      | spreed | chat        | room/Hi @all @participant2 @"group/attendees1" bye | participant1-displayname replied to your message in conversation room |
+
   Scenario: Delete notification when the message is deleted
     When user "participant1" creates room "one-to-one room" (v4)
       | roomType | 1 |
@@ -355,7 +435,7 @@ Feature: chat/notifications
       | app    | object_type | object_id                 | subject                                                                       |
       | spreed | chat        | room/Hi @participant2     | participant1-displayname mentioned you in conversation room                   |
       | spreed | chat        | room/Message 1            | participant1-displayname reacted with 🚀 to your message in conversation room |
-      | spreed | chat        | room/Hi @all bye          | participant1-displayname mentioned you in conversation room                   |
+      | spreed | chat        | room/Hi @all bye          | participant1-displayname mentioned everyone in conversation room              |
 
   Scenario: Lobby: Notifications for moderators
     Given user "participant1" creates room "room" (v4)
@@ -376,7 +456,7 @@ Feature: chat/notifications
       | app    | object_type | object_id                 | subject                                                                       |
       | spreed | chat        | room/Hi @participant2     | participant1-displayname mentioned you in conversation room                   |
       | spreed | chat        | room/Message 1            | participant1-displayname reacted with 🚀 to your message in conversation room |
-      | spreed | chat        | room/Hi @all bye          | participant1-displayname mentioned you in conversation room                   |
+      | spreed | chat        | room/Hi @all bye          | participant1-displayname mentioned everyone in conversation room              |
 
   Scenario: Lobby: Wipe notifications when being blocked by the lobby
     Given user "participant1" creates room "room" (v4)
@@ -395,7 +475,7 @@ Feature: chat/notifications
       | app    | object_type | object_id                 | subject                                                                       |
       | spreed | chat        | room/Hi @participant2     | participant1-displayname mentioned you in conversation room                   |
       | spreed | chat        | room/Message 1            | participant1-displayname reacted with 🚀 to your message in conversation room |
-      | spreed | chat        | room/Hi @all bye          | participant1-displayname mentioned you in conversation room                   |
+      | spreed | chat        | room/Hi @all bye          | participant1-displayname mentioned everyone in conversation room              |
     When user "participant1" sets lobby state for room "room" to "non moderators" with 200 (v4)
     Then user "participant2" has the following notifications
       | app | object_type | object_id | subject |
diff --git a/tests/php/Chat/AutoComplete/SearchPluginTest.php b/tests/php/Chat/AutoComplete/SearchPluginTest.php
index 0b281e53f48..441007e107b 100644
--- a/tests/php/Chat/AutoComplete/SearchPluginTest.php
+++ b/tests/php/Chat/AutoComplete/SearchPluginTest.php
@@ -21,6 +21,7 @@
 
 namespace OCA\Talk\Tests\php\Chat\AutoComplete;
 
+use OC\Collaboration\Collaborators\SearchResult;
 use OCA\Talk\Chat\AutoComplete\SearchPlugin;
 use OCA\Talk\Files\Util;
 use OCA\Talk\GuestManager;
@@ -31,6 +32,8 @@
 use OCA\Talk\Service\ParticipantService;
 use OCA\Talk\TalkSession;
 use OCP\Collaboration\Collaborators\ISearchResult;
+use OCP\IGroup;
+use OCP\IGroupManager;
 use OCP\IL10N;
 use OCP\IUser;
 use OCP\IUserManager;
@@ -42,6 +45,8 @@ class SearchPluginTest extends TestCase {
 	protected $userManager;
 	/** @var GuestManager|MockObject */
 	protected $guestManager;
+	/** @var IGroupManager|MockObject */
+	protected $groupManager;
 	/** @var TalkSession|MockObject */
 	protected $talkSession;
 	/** @var ParticipantService|MockObject */
@@ -57,6 +62,7 @@ public function setUp(): void {
 		parent::setUp();
 
 		$this->userManager = $this->createMock(IUserManager::class);
+		$this->groupManager = $this->createMock(IGroupManager::class);
 		$this->guestManager = $this->createMock(GuestManager::class);
 		$this->talkSession = $this->createMock(TalkSession::class);
 		$this->participantService = $this->createMock(ParticipantService::class);
@@ -78,6 +84,7 @@ protected function getPlugin(array $methods = []) {
 		if (empty($methods)) {
 			return new SearchPlugin(
 				$this->userManager,
+				$this->groupManager,
 				$this->guestManager,
 				$this->talkSession,
 				$this->participantService,
@@ -90,6 +97,7 @@ protected function getPlugin(array $methods = []) {
 		return $this->getMockBuilder(SearchPlugin::class)
 			->setConstructorArgs([
 				$this->userManager,
+				$this->groupManager,
 				$this->guestManager,
 				$this->talkSession,
 				$this->participantService,
@@ -313,4 +321,54 @@ public function testCreateGuestResult(string $actorId, string $name, array $expe
 		$plugin = $this->getPlugin();
 		$this->assertEquals($expected, self::invokePrivate($plugin, 'createGuestResult', [$actorId, $name]));
 	}
+
+	/**
+	 * @dataProvider dataSearchGroups
+	 */
+	public function testSearchGroups($search, $groupIds, $isGroup, $displayName, $totalMatches, $totalExactMatches): void {
+		$this->groupManager
+			->method('get')
+			->willReturnCallback(function ($groupId) use ($isGroup, $displayName) {
+				if ($isGroup) {
+					$group = $this->createMock(IGroup::class);
+					$group
+						->method('getDisplayName')
+						->willReturn($displayName);
+					$group
+						->method('getGID')
+						->willReturn($groupId);
+					return $group;
+				}
+			});
+		$plugin = $this->getPlugin(['createGroupResult']);
+		$plugin->expects($this->any())
+			->method('createGroupResult')
+			->willReturnCallback(function ($groupId) {
+				return [
+					'label' => $groupId,
+					'value' => [
+						'shareType' => 'group',
+						'shareWith' => 'group/' . $groupId,
+					],
+				];
+			});
+		$searchResult = new SearchResult();
+		self::invokePrivate($plugin, 'searchGroups', [$search, $groupIds, $searchResult]);
+		$actual = $searchResult->asArray();
+		$this->assertCount($totalMatches, $actual['groups']);
+		$this->assertCount($totalExactMatches, $actual['exact']['groups']);
+	}
+
+	public function dataSearchGroups(): array {
+		return [
+			// $search, $groupIds, $isGroup, $displayName, $totalMatches, $totalExactMatches
+			['',        ['groupid'], true,  'group', 1, 0],
+			['groupid', ['groupid'], true,  'group', 0, 1],
+			['gro',     ['groupid'], true,  'group', 1, 0],
+			['not',     ['groupid'], false, 'group', 0, 0],
+			['name',    ['groupid'], true,  'name',  0, 1],
+			['na',      ['groupid'], true,  'name',  1, 0],
+			['not',     ['groupid'], true,  'group', 0, 0],
+		];
+	}
 }
diff --git a/tests/php/Chat/NotifierTest.php b/tests/php/Chat/NotifierTest.php
index 9443210799c..2249ba6c545 100644
--- a/tests/php/Chat/NotifierTest.php
+++ b/tests/php/Chat/NotifierTest.php
@@ -36,6 +36,7 @@
 use OCP\AppFramework\Utility\ITimeFactory;
 use OCP\Comments\IComment;
 use OCP\IConfig;
+use OCP\IGroupManager;
 use OCP\Notification\IManager as INotificationManager;
 use OCP\Notification\INotification;
 use OCP\IUserManager;
@@ -47,6 +48,8 @@ class NotifierTest extends TestCase {
 	protected $notificationManager;
 	/** @var IUserManager|MockObject */
 	protected $userManager;
+	/** @var IGroupManager|MockObject */
+	protected $groupManager;
 	/** @var ParticipantService|MockObject */
 	protected $participantService;
 	/** @var Manager|MockObject */
@@ -69,6 +72,7 @@ public function setUp(): void {
 			->willReturnCallback(function ($userId) {
 				return $userId !== 'unknownUser';
 			});
+		$this->groupManager = $this->createMock(IGroupManager::class);
 
 		$this->participantService = $this->createMock(ParticipantService::class);
 		$this->manager = $this->createMock(Manager::class);
@@ -87,6 +91,7 @@ protected function getNotifier(array $methods = []) {
 				->setConstructorArgs([
 					$this->notificationManager,
 					$this->userManager,
+					$this->groupManager,
 					$this->participantService,
 					$this->manager,
 					$this->config,
@@ -99,6 +104,7 @@ protected function getNotifier(array $methods = []) {
 		return new Notifier(
 			$this->notificationManager,
 			$this->userManager,
+			$this->groupManager,
 			$this->participantService,
 			$this->manager,
 			$this->config,
@@ -164,18 +170,6 @@ public function testNotifyMentionedUsers(string $message, array $alreadyNotified
 		$room = $this->getRoom();
 		$comment = $this->newComment('108', 'users', 'testUser', new \DateTime('@' . 1000000016), $message);
 		$notifier = $this->getNotifier([]);
-		$alreadyNotifiedUsers = array_map(function ($user): array {
-			return [
-				'id' => $user,
-				'type' => Attendee::ACTOR_USERS,
-			];
-		}, $alreadyNotifiedUsers);
-		$expectedReturn = array_map(function ($user): array {
-			return [
-				'id' => $user,
-				'type' => Attendee::ACTOR_USERS,
-			];
-		}, $expectedReturn);
 		$actual = $notifier->notifyMentionedUsers($room, $comment, $alreadyNotifiedUsers, false);
 
 		$this->assertEqualsCanonicalizing($expectedReturn, $actual);
@@ -186,20 +180,20 @@ public function dataNotifyMentionedUsers(): array {
 			'no notifications' => [
 				'No mentions', [], [], [],
 			],
-			'notify an unotified user' => [
-				'Mention @anotherUser', [], ['anotherUser'], ['anotherUser'],
+			'notify a mentioned user' => [
+				'Mention @anotherUser', [], [['id' => 'anotherUser', 'type' => 'users', 'reason' => 'direct']], [['id' => 'anotherUser', 'type' => 'users', 'reason' => 'direct']],
 			],
 			'not notify mentioned user if already notified' => [
-				'Mention @anotherUser', ['anotherUser'], [], ['anotherUser'],
+				'Mention @anotherUser', [['id' => 'anotherUser', 'type' => 'users', 'reason' => 'reply']], [], [['id' => 'anotherUser', 'type' => 'users', 'reason' => 'reply']],
 			],
 			'notify mentioned Users With Long Message Start Mention' => [
-				'123456789 @anotherUserWithOddLengthName 123456789-123456789-123456789-123456789-123456789-123456789', [], ['anotherUserWithOddLengthName'], ['anotherUserWithOddLengthName'],
+				'123456789 @anotherUserWithOddLengthName 123456789-123456789-123456789-123456789-123456789-123456789', [], [['id' => 'anotherUserWithOddLengthName', 'type' => 'users', 'reason' => 'direct']], [['id' => 'anotherUserWithOddLengthName', 'type' => 'users', 'reason' => 'direct']],
 			],
 			'notify mentioned users with long message middle mention' => [
-				'123456789-123456789-123456789-1234 @anotherUserWithOddLengthName 6789-123456789-123456789-123456789', [], ['anotherUserWithOddLengthName'], ['anotherUserWithOddLengthName'],
+				'123456789-123456789-123456789-1234 @anotherUserWithOddLengthName 6789-123456789-123456789-123456789', [], [['id' => 'anotherUserWithOddLengthName', 'type' => 'users', 'reason' => 'direct']], [['id' => 'anotherUserWithOddLengthName', 'type' => 'users', 'reason' => 'direct']],
 			],
 			'notify mentioned users with long message end mention' => [
-				'123456789-123456789-123456789-123456789-123456789-123456789 @anotherUserWithOddLengthName 123456789', [], ['anotherUserWithOddLengthName'], ['anotherUserWithOddLengthName'],
+				'123456789-123456789-123456789-123456789-123456789-123456789 @anotherUserWithOddLengthName 123456789', [], [['id' => 'anotherUserWithOddLengthName', 'type' => 'users', 'reason' => 'direct']], [['id' => 'anotherUserWithOddLengthName', 'type' => 'users', 'reason' => 'direct']],
 			],
 			'mention herself' => [
 				'Mention @testUser', [], [], [],
@@ -208,7 +202,9 @@ public function dataNotifyMentionedUsers(): array {
 				'Mention @unknownUser', [], [], [],
 			],
 			'notify mentioned users several mentions' => [
-				'Mention @anotherUser, and @unknownUser, and @testUser, and @userAbleToJoin', [], ['anotherUser', 'userAbleToJoin'], ['anotherUser', 'userAbleToJoin'],
+				'Mention @anotherUser, and @unknownUser, and @testUser, and @userAbleToJoin', [],
+				[['id' => 'anotherUser', 'type' => 'users', 'reason' => 'direct'], ['id' => 'userAbleToJoin', 'type' => 'users', 'reason' => 'direct']],
+				[['id' => 'anotherUser', 'type' => 'users', 'reason' => 'direct'], ['id' => 'userAbleToJoin', 'type' => 'users', 'reason' => 'direct']],
 			],
 			'notify mentioned users to user not invited to chat' => [
 				'Mention @userNotInOneToOneChat', [], [], [],
@@ -332,7 +328,7 @@ public function testAddMentionAllToList(array $usersToNotify, array $participant
 			->method('getActorsByType')
 			->willReturn($participants);
 
-		$actual = $this->invokePrivate($this->getNotifier(), 'addMentionAllToList', [$room, $usersToNotify]);
+		$actual = self::invokePrivate($this->getNotifier(), 'addMentionAllToList', [$room, $usersToNotify]);
 		$this->assertCount(count($return), $actual);
 		foreach ($actual as $key => $value) {
 			$this->assertIsArray($value);
@@ -353,25 +349,25 @@ public function dataAddMentionAllToList(): array {
 			],
 			'preserve notify list and do not notify all' => [
 				[
-					['id' => 'user1', 'type' => Attendee::ACTOR_USERS],
+					['id' => 'user1', 'type' => Attendee::ACTOR_USERS, 'reason' => 'direct'],
 				],
 				[],
 				[
-					['id' => 'user1', 'type' => Attendee::ACTOR_USERS],
+					['id' => 'user1', 'type' => Attendee::ACTOR_USERS, 'reason' => 'direct'],
 				],
 			],
 			'mention all' => [
 				[
-					['id' => 'user1', 'type' => Attendee::ACTOR_USERS],
-					['id' => 'all'],
+					['id' => 'user1', 'type' => Attendee::ACTOR_USERS, 'reason' => 'direct'],
+					['id' => 'all', 'type' => Attendee::ACTOR_USERS, 'reason' => 'direct'],
 				],
 				[
 					Attendee::fromRow(['actor_id' => 'user1', 'actor_type' => Attendee::ACTOR_USERS]),
 					Attendee::fromRow(['actor_id' => 'user2', 'actor_type' => Attendee::ACTOR_USERS]),
 				],
 				[
-					['id' => 'user1', 'type' => Attendee::ACTOR_USERS],
-					['id' => 'user2', 'type' => Attendee::ACTOR_USERS],
+					['id' => 'user1', 'type' => Attendee::ACTOR_USERS, 'reason' => 'direct'],
+					['id' => 'user2', 'type' => Attendee::ACTOR_USERS, 'reason' => 'all'],
 				],
 			],
 		];
@@ -420,7 +416,7 @@ public function dataNotifyReacted(): array {
 	 */
 	public function testGetMentionedUsers(string $message, array $expectedReturn): void {
 		$comment = $this->newComment('108', 'users', 'testUser', new \DateTime('@' . 1000000016), $message);
-		$actual = $this->invokePrivate($this->getNotifier(), 'getMentionedUsers', [$comment]);
+		$actual = self::invokePrivate($this->getNotifier(), 'getMentionedUsers', [$comment]);
 		$this->assertEqualsCanonicalizing($expectedReturn, $actual);
 	}
 
@@ -429,27 +425,27 @@ public function dataGetMentionedUsers(): array {
 			'mention one user' => [
 				'Mention @anotherUser',
 				[
-					['id' => 'anotherUser', 'type' => 'users'],
+					['id' => 'anotherUser', 'type' => Attendee::ACTOR_USERS, 'reason' => 'direct'],
 				],
 			],
 			'mention two user' => [
 				'Mention @anotherUser, and @unknownUser',
 				[
-					['id' => 'anotherUser', 'type' => 'users'],
-					['id' => 'unknownUser', 'type' => 'users'],
+					['id' => 'anotherUser', 'type' => Attendee::ACTOR_USERS, 'reason' => 'direct'],
+					['id' => 'unknownUser', 'type' => Attendee::ACTOR_USERS, 'reason' => 'direct'],
 				],
 			],
 			'mention all' => [
 				'Mention @all',
 				[
-					['id' => 'all', 'type' => 'users'],
+					['id' => 'all', 'type' => Attendee::ACTOR_USERS, 'reason' => 'direct'],
 				],
 			],
 			'mention user, all, guest and group' => [
 				'mention @test, @all, @"guest/1" @"group/1"',
 				[
-					['id' => 'test', 'type' => 'users'],
-					['id' => 'all', 'type' => 'users'],
+					['id' => 'test', 'type' => Attendee::ACTOR_USERS, 'reason' => 'direct'],
+					['id' => 'all', 'type' => Attendee::ACTOR_USERS, 'reason' => 'direct'],
 				],
 			],
 		];
@@ -460,7 +456,7 @@ public function dataGetMentionedUsers(): array {
 	 */
 	public function testGetMentionedUserIds(string $message, array $expectedReturn): void {
 		$comment = $this->newComment('108', 'users', 'testUser', new \DateTime('@' . 1000000016), $message);
-		$actual = $this->invokePrivate($this->getNotifier(), 'getMentionedUserIds', [$comment]);
+		$actual = self::invokePrivate($this->getNotifier(), 'getMentionedUserIds', [$comment]);
 		$this->assertEqualsCanonicalizing($expectedReturn, $actual);
 	}
 
diff --git a/tests/php/Chat/Parser/UserMentionTest.php b/tests/php/Chat/Parser/UserMentionTest.php
index 4627041120a..ea86699bf0b 100644
--- a/tests/php/Chat/Parser/UserMentionTest.php
+++ b/tests/php/Chat/Parser/UserMentionTest.php
@@ -34,6 +34,7 @@
 use OCA\Talk\Service\ParticipantService;
 use OCP\Comments\IComment;
 use OCP\Comments\ICommentsManager;
+use OCP\IGroupManager;
 use OCP\IL10N;
 use OCP\IUserManager;
 use PHPUnit\Framework\MockObject\MockObject;
@@ -44,6 +45,8 @@ class UserMentionTest extends TestCase {
 	protected $commentsManager;
 	/** @var IUserManager|MockObject */
 	protected $userManager;
+	/** @var IGroupManager */
+	protected $groupManager;
 	/** @var GuestManager|MockObject */
 	protected $guestManager;
 	/** @var ParticipantService|MockObject */
@@ -58,6 +61,7 @@ public function setUp(): void {
 
 		$this->commentsManager = $this->createMock(ICommentsManager::class);
 		$this->userManager = $this->createMock(IUserManager::class);
+		$this->groupManager = $this->createMock(IGroupManager::class);
 		$this->guestManager = $this->createMock(GuestManager::class);
 		$this->participantService = $this->createMock(ParticipantService::class);
 		$this->l = $this->createMock(IL10N::class);
@@ -65,6 +69,7 @@ public function setUp(): void {
 		$this->parser = new UserMention(
 			$this->commentsManager,
 			$this->userManager,
+			$this->groupManager,
 			$this->guestManager,
 			$this->participantService,
 			$this->l);
diff --git a/tests/php/Notification/NotifierTest.php b/tests/php/Notification/NotifierTest.php
index 7c1b29419c1..9bf14b38908 100644
--- a/tests/php/Notification/NotifierTest.php
+++ b/tests/php/Notification/NotifierTest.php
@@ -38,6 +38,7 @@
 use OCP\AppFramework\Utility\ITimeFactory;
 use OCP\Comments\IComment;
 use OCP\Files\IRootFolder;
+use OCP\IGroupManager;
 use OCP\IL10N;
 use OCP\IURLGenerator;
 use OCP\IUser;
@@ -60,6 +61,8 @@ class NotifierTest extends TestCase {
 	protected $config;
 	/** @var IUserManager|MockObject */
 	protected $userManager;
+	/** @var IGroupManager|MockObject */
+	protected $groupManager;
 	/** @var GuestManager|MockObject */
 	protected $guestManager;
 	/** @var IShareManager|MockObject */
@@ -93,6 +96,7 @@ public function setUp(): void {
 		$this->url = $this->createMock(IURLGenerator::class);
 		$this->config = $this->createMock(Config::class);
 		$this->userManager = $this->createMock(IUserManager::class);
+		$this->groupManager = $this->createMock(IGroupManager::class);
 		$this->guestManager = $this->createMock(GuestManager::class);
 		$this->shareManager = $this->createMock(IShareManager::class);
 		$this->manager = $this->createMock(Manager::class);
@@ -111,6 +115,7 @@ public function setUp(): void {
 			$this->url,
 			$this->config,
 			$this->userManager,
+			$this->groupManager,
 			$this->guestManager,
 			$this->shareManager,
 			$this->manager,