If you have a WP blog and a MailChimp account then you can sync them. Download the plugin “MailChimp for WordPress” and activate it.
Go to tab “MailChimp Setting” and clic on “Get your API key here”. After login you will be redirected to the “API Keys” page.
Clic on “Create a Key” and get your key.
You can back to wordpress and enter your key.