[otrs] Auto-response

Hi all, New to OTRS, I've successfully installed an OTRS 3.1.21. The mailbox fetcher is OK. All ticket I send to a configured mailbox are migrated into tickets. However, I can find how to enable auto-response (on ticket creation, update ...). Where are this options on OTRS 3.1.21 ? Regards, PS : I have created an auto-response (on admin interface) as auto-reply, but it seems not to work