diff --git a/apps/dav/lib/CalDAV/CalendarProvider.php b/apps/dav/lib/CalDAV/CalendarProvider.php
index 30eb6ae426800..857a1354bb43c 100644
--- a/apps/dav/lib/CalDAV/CalendarProvider.php
+++ b/apps/dav/lib/CalDAV/CalendarProvider.php
@@ -25,6 +25,7 @@
  */
 namespace OCA\DAV\CalDAV;
 
+use OCA\dav\lib\CalDAV\SchedulingInbox;
 use OCP\Calendar\ICalendarProvider;
 use OCP\IConfig;
 use OCP\IL10N;
@@ -69,4 +70,10 @@ public function getCalendars(string $principalUri, array $calendarUris = []): ar
 		}
 		return $iCalendars;
 	}
+
+	public function getSchedulingInboxes(string $principalUri): array {
+		return [
+			new SchedulingInbox($principalUri)
+		];
+	}
 }
diff --git a/apps/dav/lib/CalDAV/SchedulingInbox.php b/apps/dav/lib/CalDAV/SchedulingInbox.php
new file mode 100644
index 0000000000000..47d21efb56157
--- /dev/null
+++ b/apps/dav/lib/CalDAV/SchedulingInbox.php
@@ -0,0 +1,42 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * @copyright 2021 Christoph Wurst <christoph@winzerhof-wurst.at>
+ *
+ * @author 2021 Christoph Wurst <christoph@winzerhof-wurst.at>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+namespace OCA\dav\lib\CalDAV;
+
+use OCP\Calendar\ISchedulingInbox;
+
+class SchedulingInbox implements ISchedulingInbox {
+
+	/** @var string */
+	private $principalUri;
+
+	public function __construct(string $principalUri) {
+		$this->principalUri = $principalUri;
+	}
+
+	public function getAvailability(): ?string {
+		return null;
+	}
+}
diff --git a/lib/private/Calendar/Manager.php b/lib/private/Calendar/Manager.php
index 30ee60e49430f..5387f03c9aa6a 100644
--- a/lib/private/Calendar/Manager.php
+++ b/lib/private/Calendar/Manager.php
@@ -31,6 +31,11 @@
 use OCP\Calendar\ICalendarProvider;
 use OCP\Calendar\ICalendarQuery;
 use OCP\Calendar\IManager;
+use Psr\Container\ContainerInterface;
+use Psr\Log\LoggerInterface;
+use Throwable;
+use function array_map;
+use function array_merge;
 
 class Manager implements IManager {
 
@@ -47,8 +52,18 @@ class Manager implements IManager {
 	/** @var Coordinator */
 	private $coordinator;
 
-	public function __construct(Coordinator $coordinator) {
+	/** @var ContainerInterface */
+	private $container;
+
+	/** @var LoggerInterface */
+	private $logger;
+
+	public function __construct(Coordinator $coordinator,
+								ContainerInterface $container,
+								LoggerInterface $logger) {
 		$this->coordinator = $coordinator;
+		$this->container = $container;
+		$this->logger = $logger;
 	}
 
 	/**
@@ -159,9 +174,20 @@ public function searchForPrincipal(ICalendarQuery $query): array {
 		}
 
 		/** @var CalendarQuery $query */
-		$calendars = array_merge(...array_map(static function (ICalendarProvider $p) use ($query) {
-			return $p->getCalendars($query->getPrincipalUri(), $query->getCalendarUris());
-		}, $context->getCalendarProviders()));
+		$calendars = array_merge(
+			...array_map(function ($registration) use ($query) {
+				try {
+					/** @var ICalendarProvider $provider */
+					$provider = $this->container->get($registration->getService());
+				} catch (Throwable $e) {
+					$this->logger->error('Could not load calendar provider ' . $registration->getService() . ': ' . $e->getMessage(), [
+						'exception' => $e,
+					]);
+				}
+
+				return $provider->getCalendars($query->getPrincipalUri(), $query->getCalendarUris());
+			}, $context->getCalendarProviders())
+		);
 
 		$results = [];
 		/** @var ICalendar $calendar */
@@ -185,4 +211,26 @@ public function searchForPrincipal(ICalendarQuery $query): array {
 	public function newQuery(string $principalUri): ICalendarQuery {
 		return new CalendarQuery($principalUri);
 	}
+
+	public function getSchedulingInboxes(string $principalUri): array {
+		$context = $this->coordinator->getRegistrationContext();
+		if ($context === null) {
+			return [];
+		}
+
+		return array_merge(
+			...array_map(function($registration) use ($principalUri) {
+				try {
+					/** @var ICalendarProvider $provider */
+					$provider = $this->container->get($registration->getService());
+				} catch (Throwable $e) {
+					$this->logger->error('Could not load calendar provider ' . $registration->getService() . ': ' . $e->getMessage(), [
+						'exception' => $e,
+					]);
+				}
+
+				return $provider->getSchedulingInboxes($principalUri);
+			}, $context->getCalendarProviders())
+		);
+	}
 }
diff --git a/lib/public/Calendar/ICalendarProvider.php b/lib/public/Calendar/ICalendarProvider.php
index d135910b08c87..a1fec8e6872d8 100644
--- a/lib/public/Calendar/ICalendarProvider.php
+++ b/lib/public/Calendar/ICalendarProvider.php
@@ -42,4 +42,15 @@ interface ICalendarProvider {
 	 * @since 23.0.0
 	 */
 	public function getCalendars(string $principalUri, array $calendarUris = []): array;
+
+	/**
+	 * Get the principal's scheduling inboxes
+	 *
+	 * @param string $principalUri
+	 *
+	 * @return ISchedulingInbox[]]
+	 *
+	 * @since 23.0.0
+	 */
+	public function getSchedulingInboxes(string $principalUri): array;
 }
diff --git a/lib/public/Calendar/IManager.php b/lib/public/Calendar/IManager.php
index eb4113bba9966..16c01fffc5b25 100644
--- a/lib/public/Calendar/IManager.php
+++ b/lib/public/Calendar/IManager.php
@@ -147,4 +147,15 @@ public function searchForPrincipal(ICalendarQuery $query): array;
 	 * @since 23.0.0
 	 */
 	public function newQuery(string $principalUri) : ICalendarQuery;
+
+	/**
+	 * Get the principal's scheduling inboxes
+	 *
+	 * @param string $principalUri
+	 *
+	 * @return ISchedulingInbox[]]
+	 *
+	 * @since 23.0.0
+	 */
+	public function getSchedulingInboxes(string $principalUri): array;
 }
diff --git a/lib/public/Calendar/ISchedulingInbox.php b/lib/public/Calendar/ISchedulingInbox.php
new file mode 100644
index 0000000000000..e54f33ca86bb9
--- /dev/null
+++ b/lib/public/Calendar/ISchedulingInbox.php
@@ -0,0 +1,35 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * @copyright 2021 Christoph Wurst <christoph@winzerhof-wurst.at>
+ *
+ * @author 2021 Christoph Wurst <christoph@winzerhof-wurst.at>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+namespace OCP\Calendar;
+
+/**
+ * @since 23.0.0
+ */
+interface ISchedulingInbox {
+
+	public function getAvailability(): ?string;
+
+}