There are 3 kinds of Auto-Responders:
Time Based This type of auto-responder is sent to your contacts in a sequence of intervals starting from the day a contact opts-in to your campaigns. For e.g.: Day 0 (instant message), 3, 5, 7, 11, 14, 20. This can be used to send automatic message to any contact that joins your list.
Event Based This type of auto-responder is sent when the subscriber performs an action you specify. For e.g.: clicks the link, opens the message, changes personal details and subscribes to your campaigns, special occasions such as birthdays or anniversaries.
Activity Based This type of auto-responder is on a subscriber’s open and click activity. You can define a trigger on if a subscriber clicked on a link or opened your email it will also help in Online lead generation .