What is email bounce rate?
Email bounce rate is the percentage of sent emails that fail to deliver. A bounce means the receiving mail server rejected your email. Bounces are categorized as hard (permanent) or soft (temporary), and each type requires a different response.
Hard bounces vs soft bounces
| Type | Cause | Action |
|---|---|---|
| Hard bounce | Address doesn't exist, domain invalid, permanent rejection | Remove immediately, never retry |
| Soft bounce | Mailbox full, server temporarily down, message too large | Retry 2-3 times, then remove |
1. Validate emails at signup
The best way to reduce bounces is to prevent bad addresses from entering your list:
- Client-side format validation — catch typos like "[email protected]" before submission
- MX record check — verify the domain has mail servers configured
- Double opt-in — send a confirmation email and only add confirmed addresses
- Email verification API — services that check deliverability in real time
2. Clean your existing list
- Remove all hard bounce addresses permanently
- Remove addresses that have soft-bounced 3+ times consecutively
- Remove addresses that haven't engaged (opened/clicked) in 6+ months
- Run your list through an email verification service before large sends
3. Process bounces automatically
Manual bounce handling doesn't scale. Set up automatic suppression:
- Hard bounces — automatically suppress on first occurrence
- Soft bounces — retry with exponential backoff, suppress after 3 failures
- Complaint feedback — suppress any address that reports spam
RelayPost handles all of this automatically. Bounced and complained addresses are added to your suppression list in real time.
4. Monitor bounce rate by segment
Don't just track overall bounce rate. Break it down:
- By email type — transactional vs marketing
- By acquisition source — which signup forms produce the most bounces?
- By age — older addresses bounce more frequently
- By domain — some recipient domains may be blocking you specifically
5. Avoid common bounce triggers
- Don't buy or rent email lists — these have extremely high bounce rates
- Don't scrape emails from websites
- Don't send to role addresses (info@, admin@) for marketing
- Don't ignore unsubscribe requests
- Don't send from a new domain without warming up first
Related guides
Frequently asked questions
What is a good email bounce rate?
Below 2% is considered healthy. Below 1% is excellent. Above 5% is a serious problem that will damage your sender reputation. Hard bounces should be near 0% after the first send to a list — any hard bounce address should be permanently removed.
What's the difference between hard and soft bounces?
Hard bounces are permanent failures — the address doesn't exist, the domain is invalid, or the server permanently rejected your email. Soft bounces are temporary — the mailbox is full, the server is down, or the message is too large. Hard bounces must be removed immediately. Soft bounces should be retried and removed after 3 consecutive failures.
Does a high bounce rate affect deliverability?
Yes, significantly. ISPs interpret high bounce rates as a sign of poor list hygiene, which is associated with spammers. A bounce rate above 5% can trigger spam filtering or even IP/domain blacklisting.
How do I prevent bounces from new signups?
Implement double opt-in (confirmation email), validate email format on the client side, use an email verification API to check deliverability before sending, and reject disposable email addresses if appropriate for your use case.
Reduce bounces automatically
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