automated response; autoreply
Commonly used for email auto-replies, out-of-office messages, and automated system responses.
I set up an automated reply email during my vacation.
I received an automated response from the inquiry form.
自動応答 is broader, covering any automatic answering (e.g., phone systems), while 自動返信 specifically refers to sending a reply message.
Compound of 自動 (automatic) and 返信 (reply/response).