Deliverability glossary · Updated 2026-08-10
Hard bounce
A hard bounce is a permanent delivery failure — the address does not exist or the domain rejects it outright. Hard-bounced addresses must be suppressed immediately and never retried.
Hard bounces are permanent and unambiguous: no such user, no such domain, or a policy rejection that will not change. Soft bounces are temporary — a full mailbox, a server briefly unavailable — and can reasonably be retried.
The rate is the signal that mailbox providers watch most closely, because sending to addresses that do not exist is the defining behaviour of a purchased list. Above roughly 2% you are in dangerous territory; database-sourced lists have been reported bouncing at 15-35% depending on region, which will damage a domain within days.
The failure that turns a bad week into a permanent problem is suppression that does not hold. Someone hard-bounces, the list is re-uploaded next quarter, and the same dead address is emailed again. Every re-send repeats the reputation damage.
This is why suppression belongs in the import path rather than in a report. If a re-import can resurrect a bounced address, the suppression list is decorative.
How Raechly handles it
Bounced leads are suppressed permanently, and `import_leads` upserts by email without ever resurrecting a bounced or unsubscribed record. Bounce events arrive over the SES webhook and are written to the lead.
Related terms
Sending reputation
Sending reputation is the trust score mailbox providers assign to your domain and IP based on complaint rate, bounce rate, engagement and authentication history.
Spam trap
A spam trap is an email address that exists only to catch senders using poor list practices.
Inbox placement
Inbox placement is the share of delivered messages that reach the primary inbox rather than spam or a promotions tab.
Back to the full deliverability glossary, or read how these pieces fit together in how Raechly protects deliverability.