Mailchimp over the years I've used it has grown in leaps and bounds. They have added so many additional features than were previously available. They are truly an all-in-one marketing platform now.
If you're a small operation and just want to add email to your marketing efforts, they're there for you. If you're a larger operation and want to start sending postcard advertisements, they can do that. If you'd good with that and want to kick up your marketing by going social, you can do that on their platform. They are truly able to be as small as you need, but also get quite large in whatever it is you'd like to do through their system.