Hard and soft bounces
| Type | Cause | What to do |
|---|---|---|
| Hard bounce | Permanent: the address or domain does not exist. | Remove the address. |
| Soft bounce | Temporary: full mailbox, server down, message too large. | Retry, then suppress if it keeps failing. |
Why reputation depends on it
Receiving systems learn which senders are careful. A sender that repeatedly mails addresses that do not exist looks like one that collected addresses carelessly. Sending platforms often act on high bounce rates too, by warning or suspending an account.
What verification fixes, and what it does not
- It removes addresses that would hard bounce: malformed, nonexistent domain, no mail servers.
- It flags risky addresses: disposable, role accounts, catch-all domains.
- It cannot guarantee inbox placement, which also depends on authentication and engagement.
- It cannot reliably identify spam traps.
A simple routine
- Verify before the first send to any new list.
- Remove invalid addresses and review risky ones.
- Suppress addresses that hard bounce, immediately and permanently.
- Re-verify old segments before a long-delayed campaign.
- Authenticate your domain with SPF, DKIM and DMARC.
Questions
What is a good bounce rate?
Lower is better, and platforms set their own limits. The practical goal is to remove every address that would hard bounce before you send.
Does verification protect sender reputation?
It helps by removing addresses that would bounce, but reputation also depends on authentication, complaint rates and engagement.