Hard Bounce

A hard bounce is an email that cannot be delivered because of a permanent issue. Common reasons for hard bounces are typos, domains that do not exist, or email addresses that don't exist. Hard bounces negatively impact your sending reputation and deliverability and should be corrected as fast as possible.

A hard bounce differs from a soft bounce as soft bounces are temporary, and caused by full inboxes, large emails, or temporary suspensions.