You can enable Mandrill to send email using a custom domain.

Requirements

To enable the Mandrill Integration, you'll need a Mandrill API Key. You can find or create a new Mandrill API Key from your settings page.

Enable Mandrill

You can enable the Mandrill Integration by going to the Integration panel in your dashboard and dragging it from the list of available integrations.

Authenticate your sending domain

Verify Domain

Add CNAME record for DKIM for your sending domain

Add SPF record for your sending domain

Notes

Launching Mandrill from Mailchimp

You can quickly Launch Mandrill from Mailchimp by clicking the Launch Mandrill link in your Transactional settings.