diff --git a/lib/Service/SystemService.php b/lib/Service/SystemService.php
index 2a3703379..50cc9bdc0 100644
--- a/lib/Service/SystemService.php
+++ b/lib/Service/SystemService.php
@@ -121,10 +121,13 @@ class SystemService {
 		$list = [];
 		if ($query !== '') {
 			preg_match_all(self::REGEX_PARSE_MAIL, $query, $parsedQuery);
-			$emailAddress = $parsedQuery[2][0];
-			$displayName = $parsedQuery[1][0];
-			if ($emailAddress && self::isValidEmail($emailAddress)) {
-				$list[] = new Email($emailAddress, $displayName, $emailAddress);
+
+			if (!empty($parsedQuery[1]) && !empty($parsedQuery[2])) {
+				$emailAddress = $parsedQuery[2][0];
+				$displayName = $parsedQuery[1][0];
+				if ($emailAddress && self::isValidEmail($emailAddress)) {
+					$list[] = new Email($emailAddress, $displayName, $emailAddress);
+				}
 			}
 
 			$list = array_merge($list, UserBase::search($query));