What type of bounce results from a permanent delivery failure?

A hard bounce refers to a permanent delivery failure when an email cannot be delivered to a recipient's inbox. This typically occurs due to reasons such as the recipient's email address being invalid or the domain no longer existing. When a hard bounce happens, it signifies that the email was rejected outright by the receiving server, indicating that any future messages sent to that address will also likely fail.

Understanding the characteristics of a hard bounce is essential for managing email lists effectively. Taking action, like removing hard-bounced addresses from mailing lists, helps improve email deliverability and sender reputation. In contrast, soft bounces and other types of temporary issues might still resolve over time, but a hard bounce indicates a definitive problem that requires immediate attention.