wabbit -- the only thing they have are email addresses! GRNC has those email addresses because the people signed up on the GRNC website voluntarily. Read the first paragraph of the webpage that you linked, yourself:
Originally Posted by ncwabbit
In a simple, easily utilized voter guide, the Remember in November project covers nearly all state and federal candidates in North Carolina. In 2010, GRNC distributed 110,000 such voter guides, including 85,000 mailed directly to gun owners across the state.
GRNC didn't just go grabbing up email addresses at random.