Purchased lists are ineffective, and they impact everyone else who uses Mailchimp, too. If you send emails to a list of people whose contact info you bought, many of the emails will get identified as spam. Some spam filters will flag a campaign if anyone with the same IP has sent spam in the past. When you use Mailchimp, your email is delivered through our servers, so if one person sends spam, it could prevent other users’ emails from reaching inboxes. But by forbidding Mailchimp users from using purchased lists, we increase deliverability for everyone.
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.