diff --git a/lib/Controller/PageController.php b/lib/Controller/PageController.php
index 0b0633a338..ce71d0e81d 100644
--- a/lib/Controller/PageController.php
+++ b/lib/Controller/PageController.php
@@ -411,7 +411,10 @@ public function filteredDraft(string $filter, int $mailboxId, int $draftId): Tem
 	 */
 	public function compose(string $uri): RedirectResponse {
 		$parts = parse_url($uri);
-		$params = ['to' => $parts['path']];
+		$params = [];
+		if (isset($parts['path'])) {
+			$params['to'] = $parts['path'];
+		}
 		if (isset($parts['query'])) {
 			$parts = explode('&', $parts['query']);
 			foreach ($parts as $part) {
diff --git a/src/components/MailboxThread.vue b/src/components/MailboxThread.vue
index 3fce095611..bf9a032b12 100644
--- a/src/components/MailboxThread.vue
+++ b/src/components/MailboxThread.vue
@@ -368,6 +368,7 @@ export default {
 						accountId,
 						to: this.stringToRecipients(this.$route.query.to),
 						cc: this.stringToRecipients(this.$route.query.cc),
+						bcc: this.stringToRecipients(this.$route.query.bcc),
 						subject: this.$route.query.subject || '',
 						body: this.$route.query.body ? detect(this.$route.query.body) : html(''),
 					},
diff --git a/tests/Unit/Controller/PageControllerTest.php b/tests/Unit/Controller/PageControllerTest.php
index d17ce67d57..5ea42fde9b 100644
--- a/tests/Unit/Controller/PageControllerTest.php
+++ b/tests/Unit/Controller/PageControllerTest.php
@@ -40,6 +40,7 @@
 use PHPUnit\Framework\MockObject\MockObject;
 use Psr\Container\ContainerInterface;
 use Psr\Log\LoggerInterface;
+use function urlencode;
 
 class PageControllerTest extends TestCase {
 	/** @var string */
@@ -380,6 +381,17 @@ public function testComposeWithCc() {
 		$this->assertEquals($expected, $response);
 	}
 
+	public function testComposeBcc() {
+		$bcc = 'blind@example.com';
+		$uri = "mailto:?bcc=$bcc";
+
+		$expected = new RedirectResponse('?bcc=' . urlencode($bcc));
+
+		$response = $this->controller->compose($uri);
+
+		$this->assertEquals($expected, $response);
+	}
+
 	public function testComposeWithBcc() {
 		$address = 'user@example.com';
 		$bcc = 'blind@example.com';