It's not possible to have a traditional inbox for a domain as well as have Mandrill accept email for that domain. Instead, you'll likely want to have Mandrill handle only a subdomain, like inbound.domain.com, and set up the routes for that subdomain. Your root domain could then be used for traditional inboxes for sending and receiving mail.
Alternately, you can set up your root domain to be handled by Mandrill. Whenever you get mail to info@yourdomain.com, you'd process the webhook POST, and use the information from that POST to create a new outbound message to some other inbox where you can receive mail.