Ok i currently send information to my customers through my magento website. I'm curious to know what the difference is between sending emails through my website's server and using a service like mailchimp or mandrill?
Mailchimp has a lot of list management features for the admins such as sub-dividing your list into the most responsive vs least responsive subscribers so you can tailor your message to each (for example), MailChimp has your campaign analytics built into their dashboard, they have fully implemented sign-up buttons for your website, automatically sent subscription confirmation emails, and subscription management forms for the users to decide which lists they want to be on. These are just a few benefits.
Basically: You could do all that with Magento and Google Analytics and a bunch of custom backend code, but it would be a huuuge amount of work. Then again it all depends on how much you intend on focusing on email marketing. If you're sending a newsletter to a small list, then you're probably fine with sending emails from Magento.