Mandrill temporarily keeps a copy of the HTML and text parts of emails sent for your account for 30 days. View this information on the Activity page in your Mandrill account.
Click the View Content link next to a particular email to see a window that displays the contents. This link is available for thirty (30) days. For rejected emails, because the content wasn't processed or sent by Mandrill, the View Content link will display an error or no content.