Triggered mail, automation campaigns or autoresponders are a great way to stay relevant and connected with your contacts. As an example, if you send a confirmation email after someone signs up to receive your newsletter, that is a triggered email.
Get started by heading to your Campaign screen and the choose to "Create Campaign". Then, you'll see the options in the available drop down boxes for when the email should be sent based on a particular triggered event:
when a contact opens an email,
when a contact clicks an email,
when a contact is added to your trigger audience (IMPORTANT NOTE: this will only work for contacts added via Quick Add or Web Form).
You also have the option to decide when this triggered email gets sent.