One of the most important things you can do as a blogger is to build an email list from the very beginning. Growing a list of people that are interested in what you share is something that will benefit your blogging business for years and years.
When you have a client email list, it is like having a traffic funnel on demand to new blog posts & events you write or host, new product launches you develop or even an affiliate product you want to share or promote. Having a list also gives you a chance to grow your relationship with your customers even furhter.
One great benefit to having a list is you can use auto responders to automate messages to your subscribers developing a powerful marketing funnel. Once you set up your auto responder it will run and sell for you automatically letting you focus on just building your list numbers.
All these programs are opt-in programs so they are all spam compliant and most of them also offer a very easy to use user interface for designing custom emails and managing your client email lists for email distribution.