This broadly describes how well a sender can deliver an email to the stated destination or inbox.
When some email marketers want to assess the possibility of their email campaigns getting to the inboxes of their subscribers, relative to bulking, spam issues, bounces, throttling, and delivery-like ISPs, they use deliverability.
Your deliverability may suffer if you do not use a custom authentication while sending, use single opt-in, or send from a free domain email address. Other elements that may affect deliverability include low engagement, the use of URL shorteners, and the difficult unsubscribing process.
When it comes to delivery, ESPs provide you with the reasons your email was bounced in line with the details obtained from the receiving server through the error message.