The core to any business online or offline is having a list in which they can turn to. This list is used for many different things including product research to see what people want and to push further products quickly turning the list into repeat customers.
What else is important is being sure your emails are delivered to the people you send them to. With spam protectors, blacklisting and other unseen events happening with email blocking its important to know your message gets though, this is why I use Aweber. You can pick up your own trial account for just $1 the first month via this banner.