The Wysija Newsletter Plugin is the best for small sites and blogs with under 2.000 subscribers because it is tottaly free. This is the power of Wysija. It is easy to make a campaign and more easily, it automatically takes the latest posts and inserts them in the e-mail campaign.
The disadvantage is the non-style subscription form. It is very nice and for an amateur as i am, it is difficult to edit the style. Should be some premade subscription forms for selection.
P.S. If anybody has an idea or has an editted subscription form can tell us!