Deliverability refers to an email campaign’s ability to reach intended recipients and the correct inboxes (avoiding spam folders for one!).
You can improve your deliverability through learning the expectations of Internet Service Providers (ISPs), monitoring reports and statistics, building a strong and clean client list and providing a contingency plan for when your list goes bad.
When your deliverability fails, so does your marketing campaign. You can find yourself being added to blacklist upon blacklist, getting reported for spam and sending your mail to people who don’t read it. ISPs are constantly finding new ways to block your email and limit its reach and you need to stay on top of things if you expect to reach the top.