Mandrill is an email infrastructure service offered as an add-on for MailChimp.
For authentication you would need a Mandrill API key. You can find it (or generate it) in the Mandrill UI:
The technical notes page gives some technical details about Mandrillapp component like changelog.
Inbound e-mail trigger
Intbound e-mail trigger can receive e-mails that are sent to mandrill inbox(es), it uses Webhooks API.
You have following configuration parameters: