You don't need any plugins for this. The easiest way in my experience, is to use Feedburner for this. You can setup your feedburner account, so that users can enter their email address into your site to register for email updates and feedburner will automatically send a daily email with a list of all of your posts for the day.
If you setup a newsletter category for your blog with it's own RSS feed, you can setup Feedburner in the same way as above, but have it set to specifically send emails about the content from your newsletter category only.
There are feedburner plugins for WordPress, but they don't seem to have any use (or at least I haven't found one yet) as you can just add the feedburner code directly to your template.