Auto-response messages are text messages that are immediately sent to a new subscriber when they text in. Each Keyword, Website Form, and Longcode will have it's own auto-response message(s). They can be changed at any time.
Auto-response options explained
Send Every Time - the subscriber receives the auto-response message every time they text the keyword to your shortcode.
Send Once Per Number Per Keyword - the subscriber receives the auto-response message only when they initially text the keyword to your Shortcode or text in to your Longcode. If they text the keyword again, they will not receive the auto-response message.
Send Once Per Number Per Account - the subscriber receives the auto-response on their first interaction with your account. Any interactions with your account after (keyword/website form/dedicated number) will not trigger another auto-response.