diff --git a/lib/Service/ContactsIntegration.php b/lib/Service/ContactsIntegration.php
index 47b749aa7a..908ad2ca13 100644
--- a/lib/Service/ContactsIntegration.php
+++ b/lib/Service/ContactsIntegration.php
@@ -66,6 +66,12 @@ public function getMatchingRecipient(string $userId, string $term): array {
 				if ($e === '') {
 					continue;
 				}
+
+				$mightBeValidEmail = filter_var($e, FILTER_VALIDATE_EMAIL);
+				if ($mightBeValidEmail === false) {
+					continue;
+				}
+
 				$receivers[] = [
 					'id' => $id,
 					// Show full name if possible or fall back to email