Understanding the various email deliverability terms can sometimes be confusing. Here is quick overview to help you get up to speed and focus on the key terms and metrics that drive the success of your email program. Email deliverability is the process by which emails are accepted at the gateway of the ISPs and subsequently blocked or delivered to recipient inboxes, spam folders or junk folder. Good email deliverability means that the majority of your email ends up in the inbox. Delivered Rate is the percentage of emails that are accepted by the ISPs. This excludes bounces and invalid emails rejected by the server. However, delivered does not necessarily mean that your email made it to recipient inboxes. In fact, it could mean that it was delivered to the spam or junk folder. Blocks are notifications that your IP address has been put on a blacklist. If your IP has blacklisted, then delivery of your email will be negatively affected. Deferrals occur when an ISP is not ready to accept or trust email from your IP. As a result, it will chose to defer receiving your message instead of blocking it. In this case, SendGrid will attempt re-delivery for 72 hours, after which it will be placed on a hard bounce list. To learn more about email deliverability and the factors that help you make it into the inbox, download the SendGrid Deliverability Guide. It contains everything you need to know about delivering email through your application.