Mailchimp is an online marketing platform that was initially focused on email marketing services. Today the platform also offers marketing automation tools, ad creation, a website builder, landing page builder, web hosting, and more.
Mailchimp is free for users with less than 2,000 contacts and then moves to $9.95 for 50,000 contacts and or $14.95 for 100,000 contacts. More enterprise-type offerings will fall into the $299 / month pricing or above.
Reviews of Mailchimp are generally very positive, with the company at or near the top of many reviews and articles covering email marketing services.