A hard bounce is an email message that is returned to the sender because it is undeliverable. Hard bounces are typically caused by permanent delivery failures, such as an invalid or non-existent email address.
Hard bounces are different from soft bounces, which are temporary delivery failures caused by issues such as a full mailbox or a temporary server problem. Soft bounces may be successful if the email is re-sent at a later time.
Hard bounces can be a problem for businesses and organizations that use email marketing, because they can reduce the effectiveness of their campaigns and damage their sender reputation. To avoid hard bounces, it is important to maintain a clean and accurate email list, and to remove invalid or inactive email addresses.
Many email marketing platforms and services have built-in tools for detecting and handling hard bounces, such as by automatically removing invalid email addresses from the email list. These tools can help businesses and organizations maintain high email deliverability rates and protect their sender reputation.