Hard bounces
Permanent failures: invalid addresses, non-existent domains, or blocked recipients. Remove them — do not keep retrying.
Guide
Understanding and handling email bounces
Hard vs soft bounces, common causes of high bounce rates, and a practical playbook: verify first, then send.
Types
Hard vs soft bounces
Soft bounces
Temporary issues: full mailbox, greylisting, or transient server errors. Retry carefully; recurring soft bounces may need suppression.
Root causes
Why bounce rates climb
- Typos and invented addresses at capture
- Aged lists with expired or abandoned mailboxes
- Disposable inboxes that die after signup
- Role accounts and low-quality segments that never engage
- Sending without re-verifying after a long pause
Playbook
Verify first. Then send.
Gate new capture
Verify at the form so undeliverable addresses never enter the ESP.
Clean before campaigns
Run list jobs; export deliverable segments; define policy for risky flags.
Suppress hard failures
Do not re-mail addresses that hard bounce. Keep a suppression list.
Re-verify aged files
Lists decay. Re-check before re-engagement and migrations.
Cut permanent failures
Classify addresses before the next campaign
Start free. Same results in the dashboard, list jobs, and API.