diff --git a/server/plugins-available/maildeliver_plugin.inc.php b/server/plugins-available/maildeliver_plugin.inc.php
index 4c0ebd45a95860772e642b8e7e084f74aac05432..85293ae4086fd0dadec1f0db3bdfccf962a34e1c 100644
--- a/server/plugins-available/maildeliver_plugin.inc.php
+++ b/server/plugins-available/maildeliver_plugin.inc.php
@@ -219,17 +219,18 @@ class maildeliver_plugin {
 
 			file_put_contents($sieve_file_isp, $tpl->grab()) or $app->log("Unable to write sieve filter file", LOGLEVEL_WARN);
 			if ( is_file($sieve_file_isp) ) {
-				chown($sieve_file_isp,$mail_config['mailuser_name']);
-				chgrp($sieve_file_isp,$mail_config['mailuser_group']);
+				$app->system->chown($sieve_file_isp,$mail_config['mailuser_name'],false);
+				$app->system->chgrp($sieve_file_isp,$mail_config['mailuser_group'],false);
 			}
 			chdir($data["new"]["maildir"]);
 			//* create symlink to activate sieve script
 			symlink("sieve/ispconfig.sieve", ".sieve")  or $app->log("Unable to create symlink to active sieve filter", LOGLEVEL_WARN);
 			if (is_link(".sieve")) {
-				lchown(".sieve",$mail_config['mailuser_name']);
-				lchgrp(".sieve",$mail_config['mailuser_group']);
+				$app->system->chown(".sieve",$mail_config['mailuser_name'],true);
+				$app->system->chgrp(".sieve",$mail_config['mailuser_group'],true);
 			}
-			exec('chown '.$mail_config['mailuser_name'].':'.$mail_config['mailuser_group'].' '.escapeshellcmd($sieve_file));
+			$app->system->chown($sieve_file,$mail_config['mailuser_name'],true);
+			$app->system->chgrp($sieve_file,$mail_config['mailuser_group'],true);
 
 			unset($tpl);