I have been using MailChimp for almost seven years. The product keeps getting better and better with lots of useful functionality being added all of the time.
These are the things I find most helpful about MailChimp:
MailChimp also has a wealth of resources available to help users understand email best practices, understand the stats MailChimp generates and help improve the bottom lines of its users.
To MailChimp’s credit, the company goes to great efforts to keep spammers from using their product, even if it means they will lose money.
Unfortunately MailChimp does have one big drawback, the autoresponders have some bugs and the instructions can be a little hard to understand.
Overall MailChimp is a very good product that I would recommend to any small or large business.