Email marketing can take a number of different routes. There is no 'one perfect platform' for everyone so I have listed a number below. Be sure to contact me if you have any suggestions. Click any of the website names or images to be taken to their website.
Vertical Response has been around for awhile. If searching for a new email marketing service, they are worth a look and like most of these platforms there is a free starting plan.
Also listed on the Conversion list, MailMunch allows you to create great opt-in forms without any coding. Ever wonder how the website knows to send a pop up the minute you go to leave? That's a feature of MailMunch and more.