I haven’t heard of Feedblitz – just looking at their website now. Appears that they’re a Feedburner replacement specialising in RSS-to-email (sending your blog subscribers an email about latest posts). Their pricing looks a bit steep (considering Feedburner was free) – so I’d probably choose Mailchimp or Aweber over them? That way you can message up to a few thousand people free of charge.
The primary cost of poorly crafted or mis-targeted emails is lost business opportunities, though in extreme cases it can damage a firm’s reputation as well. But the potential payoff for effective email marketing is substantial; email messages are more likely to be seen and acted upon by decision makers than online content, social media, or advertising.