You can choose to send your mail campaign to an entire list, a pre-defined subgroup or email addresses that you select manually. Before you send, you can preview the email to see what it looks like in html. If you're prepared to pay you can also use MailChimp's Inbox Inspection and Delivery Doctor services to see what the campaign will look like in various email clients and how it will fare against common spam filters.
It's once your campaign is sent, however, that the magic really starts. Using the Reports feature, you can see how many recipients have received your mail, how many opened it, exactly who opened it and when, the clickthrough rate on any links you included in the mail and so on. You can even run a split campaign, with different versions going out to different control groups. When it's clear which version works best, you send that to the rest of the list. This kind of information is what makes email marketing worthwhile. Without it, the whole thing's a guessing game and you have no idea what your return is.
As you'd expect, MailChimp also integrates with common social networks. It's currently trialling its "social pro" feature, which queries Facebook, Twitter and other social networks to see who on your list is a member, who follows you on Twitter, how influential they are with other members and so on. Sadly, this is only free until March 2011. Even without it you can still share your campaigns on Facebook and Twitter at the touch of a button.
Verdict
MailChimp is a very good email marketing tool for small businesses. It lets you create good looking campaigns, manage your mailing lists and track the effectiveness of your marketing.
SYSTEM REQUIREMENTS
Broadband connection and modern Web browser