One of the best newsletter plugins for any WP site. it has a lot of features allowing you to control your own email list without using an external source and custom creation of your newsletter.
Still testing, but so far "AWESOME"... and support was great with quick answers to any issue. Could I ask for more sure, but out of the box Wysija did its job; an looks like they had fitted a need for bloggers to rearch their readers.
Think twice about something else.