How do autoresponders work?
Autoresponders allow you to send an email to users after they start a new issue (either via the web interface or through email). To set up autoresponders, go into your Site's Admin → Site Settings → Email Setup → Autoresponders.
From there you can create any number of autoresponders and attach them to a category. Each category can only have one autoresponder attached. After you attach this autoresponder, when users start a new discussion in a given category, they will receive the autoresponse via email.
To learn more about how to include suggested FAQs, user's emails, names and other info, visit the Autoresponder Syntax page.