diff --git a/lib/Chat/Parser/SystemMessage.php b/lib/Chat/Parser/SystemMessage.php
index 27352b275fa..225a639ab65 100644
--- a/lib/Chat/Parser/SystemMessage.php
+++ b/lib/Chat/Parser/SystemMessage.php
@@ -367,7 +367,7 @@ public function parseMessage(Message $chatMessage): void {
 				$parsedMessage = $this->l->t('An administrator demoted {user} from moderator');
 			}
 		} elseif ($message === 'guest_moderator_promoted') {
-			$parsedParameters['user'] = $this->getGuest($room, $parameters['session']);
+			$parsedParameters['user'] = $this->getGuest($room, Attendee::ACTOR_GUESTS, $parameters['session']);
 			$parsedMessage = $this->l->t('{actor} promoted {user} to moderator');
 			if ($currentUserIsActor) {
 				$parsedMessage = $this->l->t('You promoted {user} to moderator');
@@ -380,7 +380,7 @@ public function parseMessage(Message $chatMessage): void {
 				$parsedMessage = $this->l->t('An administrator promoted {user} to moderator');
 			}
 		} elseif ($message === 'guest_moderator_demoted') {
-			$parsedParameters['user'] = $this->getGuest($room, $parameters['session']);
+			$parsedParameters['user'] = $this->getGuest($room, Attendee::ACTOR_GUESTS, $parameters['session']);
 			$parsedMessage = $this->l->t('{actor} demoted {user} from moderator');
 			if ($currentUserIsActor) {
 				$parsedMessage = $this->l->t('You demoted {user} from moderator');
@@ -660,8 +660,8 @@ protected function getActorFromComment(Room $room, IComment $comment): array {
 	}
 
 	protected function getActor(Room $room, string $actorType, string $actorId): array {
-		if ($actorType === Attendee::ACTOR_GUESTS) {
-			return $this->getGuest($room, $actorId);
+		if ($actorType === Attendee::ACTOR_GUESTS || $actorType === Attendee::ACTOR_EMAILS) {
+			return $this->getGuest($room, $actorType, $actorId);
 		}
 		if ($actorType === Attendee::ACTOR_FEDERATED_USERS) {
 			return $this->getRemoteUser($actorId);
@@ -769,23 +769,26 @@ protected function loadCircleDetails(string $circleId): void {
 		}
 	}
 
-	protected function getGuest(Room $room, string $actorId): array {
-		if (!isset($this->guestNames[$actorId])) {
-			$this->guestNames[$actorId] = $this->getGuestName($room, $actorId);
+	protected function getGuest(Room $room, string $actorType, string $actorId): array {
+		$key = $room->getId() . '/' . $actorType . '/' . $actorId;
+		if (!isset($this->guestNames[$key])) {
+			$this->guestNames[$key] = $this->getGuestName($room, $actorType, $actorId);
 		}
 
 		return [
 			'type' => 'guest',
 			'id' => 'guest/' . $actorId,
-			'name' => $this->guestNames[$actorId],
+			'name' => $this->guestNames[$key],
 		];
 	}
 
-	protected function getGuestName(Room $room, string $actorId): string {
+	protected function getGuestName(Room $room, string $actorType, string $actorId): string {
 		try {
-			$participant = $room->getParticipantByActor(Attendee::ACTOR_GUESTS, $actorId);
+			$participant = $room->getParticipantByActor($actorType, $actorId);
 			$name = $participant->getAttendee()->getDisplayName();
-			if ($name === '') {
+			if ($name === '' && $actorType === Attendee::ACTOR_EMAILS) {
+				$name = $actorId;
+			} elseif ($name === '') {
 				return $this->l->t('Guest');
 			}
 			return $this->l->t('%s (guest)', [$name]);
diff --git a/tests/php/Chat/Parser/SystemMessageTest.php b/tests/php/Chat/Parser/SystemMessageTest.php
index 5f0bce5f125..ec5f5543b2d 100644
--- a/tests/php/Chat/Parser/SystemMessageTest.php
+++ b/tests/php/Chat/Parser/SystemMessageTest.php
@@ -492,7 +492,7 @@ public function testParseMessage(string $message, array $parameters, $recipientI
 			->willReturn(['id' => $parameters['group'] ?? 'group', 'type' => 'group']);
 		$parser->expects($this->any())
 			->method('getGuest')
-			->with($room, $parameters['session'] ?? 'guest')
+			->with($room, Attendee::ACTOR_GUESTS, $parameters['session'] ?? 'guest')
 			->willReturn(['id' => $parameters['session'] ?? 'guest', 'type' => 'guest']);
 
 		if ($message === 'call_ended') {
@@ -885,7 +885,7 @@ public function testGetActor(string $actorType, array $guestData, array $userDat
 		} else {
 			$parser->expects($this->once())
 				->method('getGuest')
-				->with($room, 'author-id')
+				->with($room, Attendee::ACTOR_GUESTS, 'author-id')
 				->willReturn($guestData);
 		}
 
@@ -1041,40 +1041,65 @@ public function testGetDisplayNameGroup(string $gid, bool $validGroup, string $n
 		self::assertSame($name, self::invokePrivate($parser, 'getDisplayNameGroup', [$gid]));
 	}
 
-	public function testGetGuest() {
-		$actorId = sha1('name');
+	public function dataGetGuest(): array {
+		return [
+			[Attendee::ACTOR_GUESTS, sha1('name')],
+			[Attendee::ACTOR_EMAILS, 'test@test.tld'],
+		];
+	}
 
+	/**
+	 * @dataProvider dataGetGuest
+	 * @param string $attendeeType
+	 * @param string $actorId
+	 */
+	public function testGetGuest(string $attendeeType, string $actorId): void {
 		/** @var Room|MockObject $room */
 		$room = $this->createMock(Room::class);
 
 		$parser = $this->getParser(['getGuestName']);
 		$parser->expects($this->once())
 			->method('getGuestName')
-			->with($room, $actorId)
+			->with($room, $attendeeType, $actorId)
 			->willReturn('name');
 
 		$this->assertSame([
 			'type' => 'guest',
 			'id' => 'guest/' . $actorId,
 			'name' => 'name',
-		], self::invokePrivate($parser, 'getGuest', [$room, $actorId]));
+		], self::invokePrivate($parser, 'getGuest', [$room, $attendeeType, $actorId]));
 
 		// Cached call: no call to getGuestName() again
 		$this->assertSame([
 			'type' => 'guest',
 			'id' => 'guest/' . $actorId,
 			'name' => 'name',
-		], self::invokePrivate($parser, 'getGuest', [$room, $actorId]));
+		], self::invokePrivate($parser, 'getGuest', [$room, $attendeeType, $actorId]));
 	}
 
-	public function testGetGuestName() {
-		$actorId = sha1('name');
+	public function dataGetGuestName(): array {
+		return [
+			[Attendee::ACTOR_GUESTS, sha1('name'), 'name', 'name (guest)'],
+			[Attendee::ACTOR_GUESTS, sha1('name'), '', 'Guest'],
+			[Attendee::ACTOR_EMAILS, 'test@test.tld', 'name', 'name (guest)'],
+			[Attendee::ACTOR_EMAILS, 'test@test.tld', '', 'test@test.tld (guest)'],
+		];
+	}
+
+	/**
+	 * @dataProvider dataGetGuestName
+	 * @param string $actorType
+	 * @param string $actorId
+	 * @param string $attendeeName
+	 * @param string $expected
+	 */
+	public function testGetGuestName(string $actorType, string $actorId, string $attendeeName, string $expected): void {
 
 		/** @var Room|MockObject $room */
 		$room = $this->createMock(Room::class);
 
 		$attendee = Attendee::fromParams([
-			'displayName' => 'name',
+			'displayName' => $attendeeName,
 		]);
 
 		/** @var Participant|MockObject $room */
@@ -1083,12 +1108,12 @@ public function testGetGuestName() {
 			->willReturn($attendee);
 
 		$room->method('getParticipantByActor')
-			->with(Attendee::ACTOR_GUESTS, $actorId)
+			->with($actorType, $actorId)
 			->willReturn($participant);
 
 		$parser = $this->getParser();
 		self::invokePrivate($parser, 'l', [$this->l]);
-		$this->assertSame('name (guest)', self::invokePrivate($parser, 'getGuestName', [$room, $actorId]));
+		$this->assertSame($expected, self::invokePrivate($parser, 'getGuestName', [$room, $actorType, $actorId]));
 	}
 
 	public function testGetGuestNameThrows() {
@@ -1103,7 +1128,7 @@ public function testGetGuestNameThrows() {
 
 		$parser = $this->getParser();
 		self::invokePrivate($parser, 'l', [$this->l]);
-		$this->assertSame('Guest', self::invokePrivate($parser, 'getGuestName', [$room, $actorId]));
+		$this->assertSame('Guest', self::invokePrivate($parser, 'getGuestName', [$room, Attendee::ACTOR_GUESTS, $actorId]));
 	}
 
 	public function dataParseCall(): array {