When drafting an email blast, one of the first actions you will take is setting your email recipients. You'll be asked to differentiate between Supporters or Prospects then you can choose a tag, list, or filter as recipients of your blast.

If you're importing a new list and want to send an email blast to them, you'll want to take advantage of the import customization options. You can add a tag to everyone you import, or add everyone you import to a list. This makes targeting new additions to your nation a breeze.