We could still integrate Mailchimp by automatically adding users to lists when the sign up. If there is an admin page, we could allow them to provide Mailchip list IDs for each category, and automatically add the user to the mailing list for each on account confirmation.
We could still integrate Mailchimp by automatically adding users to lists when the sign up. If there is an admin page, we could allow them to provide Mailchip list IDs for each category, and automatically add the user to the mailing list for each on account confirmation.