Not all email addresses are equal: some are healthier than others. When an email address becomes unhealthy, it may end up on an email blacklist, which can render it useless. There are many factors that influence the health of an email address, including spam trap hits, unengaged recipients, spam complaints, unsubscribes, and hard bounces, just to name a few. In general, unhealthy email addresses send low-quality emails that their recipients don’t look forward to, while healthy email addresses do the opposite. The problem is that you may seemingly do everything right and still end up on an email blacklist (more about email blacklists and how to remove an IP address or domain name from them at the end of this article). Why? The answer often boils down to misconfigured DNS records. More specifically, SPS, DMARC, and MX DNS records.