A hard bounce occurs when an email permanently cannot be delivered. This means that the email address either does not exist or is permanently unreachable.
Typical causes of a hard bounce
- Invalid or misspelled email address
- Email account that does not (or no longer) exist
- Invalid or unreachable domain
- Permanent block by the receiving mail server
A hard bounce is not temporary – unlike a soft bounce, no further delivery attempt is made.
What happens after a hard bounce?
- The email is not sent again.
- The recipient is automatically blocked or flagged to prevent further delivery attempts.
- The bounce is logged in the delivery reports and usually contains a technical error message.
Why is this relevant?
Hard bounces have a negative impact on sender reputation. A high bounce rate can cause emails to end up in the spam folder more often or to be blocked by mail servers.
Note for Leadnodes users
If you expect to receive emails from Leadnodes – e.g. login codes, lead notifications or system messages – and they do not arrive, a hard bounce may be the cause.
In this case, please contact our support team. We will be happy to check whether your address has been blocked.