diff --git a/apps/dav/lib/CalDAV/ResourceBooking/AbstractPrincipalBackend.php b/apps/dav/lib/CalDAV/ResourceBooking/AbstractPrincipalBackend.php
index d658c3433f..90d147f674 100644
--- a/apps/dav/lib/CalDAV/ResourceBooking/AbstractPrincipalBackend.php
+++ b/apps/dav/lib/CalDAV/ResourceBooking/AbstractPrincipalBackend.php
@@ -244,6 +244,14 @@ abstract class AbstractPrincipalBackend implements BackendInterface {
 					$stmt->closeCursor();
 					break;
 
+				case '{urn:ietf:params:xml:ns:caldav}calendar-user-address-set':
+					// If you add support for more search properties that qualify as a user-address,
+					// please also add them to the array below
+					$results[] = $this->searchPrincipals($this->principalPrefix, [
+						'{http://sabredav.org/ns}email-address' => $value,
+					], 'anyof');
+					break;
+
 				default:
 					$results[] = [];
 					break;
diff --git a/apps/dav/lib/Connector/Sabre/Principal.php b/apps/dav/lib/Connector/Sabre/Principal.php
index e781618539..812f9d5416 100644
--- a/apps/dav/lib/Connector/Sabre/Principal.php
+++ b/apps/dav/lib/Connector/Sabre/Principal.php
@@ -287,6 +287,16 @@ class Principal implements BackendInterface {
 					}, []);
 					break;
 
+				case '{urn:ietf:params:xml:ns:caldav}calendar-user-address-set':
+					// If you add support for more search properties that qualify as a user-address,
+					// please also add them to the array below
+					$results[] = $this->searchUserPrincipals([
+						// In theory this should also search for principal:principals/users/...
+						// but that's used internally only anyway and i don't know of any client querying that
+						'{http://sabredav.org/ns}email-address' => $value,
+					], 'anyof');
+					break;
+
 				default:
 					$results[] = [];
 					break;
diff --git a/apps/dav/lib/DAV/GroupPrincipalBackend.php b/apps/dav/lib/DAV/GroupPrincipalBackend.php
index 02f8edf392..a797a25f90 100644
--- a/apps/dav/lib/DAV/GroupPrincipalBackend.php
+++ b/apps/dav/lib/DAV/GroupPrincipalBackend.php
@@ -222,6 +222,13 @@ class GroupPrincipalBackend implements BackendInterface {
 					}, []);
 					break;
 
+				case '{urn:ietf:params:xml:ns:caldav}calendar-user-address-set':
+					// If you add support for more search properties that qualify as a user-address,
+					// please also add them to the array below
+					$results[] = $this->searchPrincipals(self::PRINCIPAL_PREFIX, [
+					], 'anyof');
+					break;
+
 				default:
 					$results[] = [];
 					break;
diff --git a/apps/dav/tests/unit/CalDAV/ResourceBooking/AbstractPrincipalBackendTest.php b/apps/dav/tests/unit/CalDAV/ResourceBooking/AbstractPrincipalBackendTest.php
index aca36fb77e..19da1782cc 100644
--- a/apps/dav/tests/unit/CalDAV/ResourceBooking/AbstractPrincipalBackendTest.php
+++ b/apps/dav/tests/unit/CalDAV/ResourceBooking/AbstractPrincipalBackendTest.php
@@ -519,6 +519,125 @@ abstract class AbstractPrincipalBackendTest extends TestCase {
 		];
 	}
 
+	public function testSearchPrincipalsByCalendarUserAddressSet() {
+		$user = $this->createMock(IUser::class);
+		$this->userSession->expects($this->exactly(2))
+			->method('getUser')
+			->with()
+			->will($this->returnValue($user));
+		$this->groupManager->expects($this->exactly(2))
+			->method('getUserGroupIds')
+			->with($user)
+			->will($this->returnValue(['group1', 'group2']));
+
+		$queryBuilder1 = $this->createMock(IQueryBuilder::class);
+		$stmt1 = $this->createMock(\Doctrine\DBAL\Driver\Statement::class);
+		$expr1 = $this->createMock(\OCP\DB\QueryBuilder\IExpressionBuilder::class);
+
+		$this->dbConnection->expects($this->at(0))
+			->method('getQueryBuilder')
+			->with()
+			->will($this->returnValue($queryBuilder1));
+		$this->dbConnection->expects($this->at(1))
+			->method('escapeLikeParameter')
+			->with('foo')
+			->will($this->returnValue('escapedFoo'));
+
+		$queryBuilder1->method('expr')
+			->will($this->returnValue($expr1));
+
+		$expr1->method('iLike')
+			->will($this->returnValueMap([
+				['email', 'createNamedParameter-1', null, 'ILIKE_CLAUSE_1'],
+			]));
+
+		$queryBuilder1->method('expr')
+			->will($this->returnValue($expr1));
+
+		$queryBuilder1->method('createNamedParameter')
+			->will($this->returnValueMap([
+				['%escapedFoo%', \PDO::PARAM_STR, null, 'createNamedParameter-1'],
+			]));
+
+		$queryBuilder1->expects($this->at(0))
+			->method('select')
+			->with(['id', 'backend_id', 'resource_id', 'email', 'displayname', 'group_restrictions'])
+			->will($this->returnValue($queryBuilder1));
+		$queryBuilder1->expects($this->at(1))
+			->method('from')
+			->with($this->expectedDbTable)
+			->will($this->returnValue($queryBuilder1));
+		$queryBuilder1->expects($this->at(4))
+			->method('where')
+			->with('ILIKE_CLAUSE_1')
+			->will($this->returnValue($queryBuilder1));
+		$queryBuilder1->expects($this->at(5))
+			->method('execute')
+			->with()
+			->will($this->returnValue($stmt1));
+
+		$stmt1->expects($this->at(0))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue([
+				'id' => 0,
+				'backend_id' => 'db',
+				'resource_id' => '1',
+				'email' => '1',
+				'displayname' => 'Resource 1',
+				'group_restrictions' => null,
+			]));
+		$stmt1->expects($this->at(1))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue([
+				'id' => 1,
+				'backend_id' => 'db',
+				'resource_id' => '2',
+				'email' => '2',
+				'displayname' => 'Resource 2',
+				'group_restrictions' => '',
+			]));
+		$stmt1->expects($this->at(2))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue([
+				'id' => 2,
+				'backend_id' => 'db',
+				'resource_id' => '3',
+				'email' => '3',
+				'displayname' => 'Resource 3',
+				'group_restrictions' => '["group3"]',
+			]));
+		$stmt1->expects($this->at(3))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue([
+				'id' => 99,
+				'backend_id' => 'db',
+				'resource_id' => '99',
+				'email' => '99',
+				'displayname' => 'Resource 99',
+				'group_restrictions' => '["group1", "group2"]',
+			]));
+		$stmt1->expects($this->at(4))
+			->method('fetch')
+			->with(\PDO::FETCH_ASSOC)
+			->will($this->returnValue(null));
+
+		$actual = $this->principalBackend->searchPrincipals($this->principalPrefix, [
+			'{urn:ietf:params:xml:ns:caldav}calendar-user-address-set' => 'foo',
+		]);
+
+		$this->assertEquals(
+			str_replace('%prefix%', $this->principalPrefix, [
+				'%prefix%/db-1',
+				'%prefix%/db-2',
+				'%prefix%/db-99',
+			]),
+			$actual);
+	}
+
 	public function testSearchPrincipalsEmptySearchProperties() {
 		$this->userSession->expects($this->never())
 			->method('getUser');
diff --git a/apps/dav/tests/unit/Connector/Sabre/PrincipalTest.php b/apps/dav/tests/unit/Connector/Sabre/PrincipalTest.php
index b40cd3105a..225189e7d0 100644
--- a/apps/dav/tests/unit/Connector/Sabre/PrincipalTest.php
+++ b/apps/dav/tests/unit/Connector/Sabre/PrincipalTest.php
@@ -391,6 +391,32 @@ class PrincipalTest extends TestCase {
 		];
 	}
 
+	public function testSearchPrincipalByCalendarUserAddressSet() {
+		$this->shareManager->expects($this->exactly(2))
+			->method('shareAPIEnabled')
+			->will($this->returnValue(true));
+
+		$this->shareManager->expects($this->exactly(2))
+			->method('shareWithGroupMembersOnly')
+			->will($this->returnValue(false));
+
+		$user2 = $this->createMock(IUser::class);
+		$user2->method('getUID')->will($this->returnValue('user2'));
+		$user3 = $this->createMock(IUser::class);
+		$user3->method('getUID')->will($this->returnValue('user3'));
+
+		$this->userManager->expects($this->at(0))
+			->method('getByEmail')
+			->with('user@example.com')
+			->will($this->returnValue([$user2, $user3]));
+
+		$this->assertEquals([
+				'principals/users/user2',
+				'principals/users/user3',
+			], $this->connector->searchPrincipals('principals/users',
+			['{urn:ietf:params:xml:ns:caldav}calendar-user-address-set' => 'user@example.com']));
+	}
+
 	public function testFindByUriSharingApiDisabled() {
 		$this->shareManager->expects($this->once())
 			->method('shareApiEnabled')