Mailchimp requires that a physical address be submitted upon account setup, and it appears once upon email list signup. It can be a little bit confusing to figure out where to change your physical address in Mailchimp, so here is a quick guide to how to change your address in Mailchimp.
Log into your account at www.mailchimp.com and in the upper right corner, under your username, navigate to Profile
Go to Settings > Contact Information
On the Contact Information page, simply scroll down to the Primary Account Contact setting, and here you can edit your physical address.
Because a physical mailing address is required by Mailchimp to meet the CAN-SPAM act and FTC spam laws, Mailchimp offers a number of alternatives to a home address and ideas you can check out here.
And if you prefer not to use Mailchimp due to this restriction, you can also follow my tutorial here to set up WordPress Jetpack which delivers blog posts via email. While you cannot edit the email template with your own branding and it is not as attractive, WordPress.com does not require a physical mailing address be submitted.