Hard Bounce
01 Definition
Hard Bounce meaning: A permanent delivery failure, usually from an invalid or nonexistent email address.
A hard bounce is an email that permanently failed to deliver, typically because the address is invalid, the domain does not exist, or the server blocked it outright. These addresses should be removed immediately, since resending to them damages sender reputation and wastes send volume. Hard bounces will not succeed on retry.
Why it matters
How Hard Bounce fits the work
Hard bounces flag addresses you should never mail again, and acting on them quickly protects your reputation and keeps deliverability metrics honest.
In context
The email hard bounced because the recipient's address had a typo in the domain, so the system flagged it for permanent removal.
Practical note
Most ESPs auto-suppress hard bounces, but if you export and reuse lists elsewhere, carry the suppression over or you will re-mail dead addresses and hurt reputation.