What is a Bounce Email? (And Why It’s Killing Your Deliverability in 2025)
Bounce emails are those that fail to reach the recipient's inbox and are returned (or "bounced back") to the sender. This can happen for a variety of reasons — some temporary, others permanent.
🧠 Why Do Emails Bounce?
Emails can bounce for several reasons, commonly categorized as:
- Hard Bounce: Permanent failure due to an invalid or non-existent email address.
- Soft Bounce: Temporary issue like a full inbox, server downtime, or large attachment.
📊 Common Bounce Causes
| Reason | Type | Explanation |
|---|---|---|
| Email address does not exist | Hard | The domain or mailbox is invalid |
| Recipient's mailbox is full | Soft | Storage limit reached |
| Server temporarily unavailable | Soft | Maintenance or overload |
| Blocklisted or flagged sender | Hard | Spam filters rejected the message |
| Misconfigured DNS or SPF records | Hard | Email server authentication failed |
🛡️ Why Bounce Rates Matter
High bounce rates damage your sender reputation, lower your deliverability, and can even get you blacklisted by email service providers.
A healthy bounce rate should stay under 2%. Anything higher signals issues with your email list or sending infrastructure.
✅ How to Reduce Bounce Emails
- 🔍 Validate email addresses before sending.
- 📤 Use verified SMTP and proper DNS setup (SPF, DKIM, DMARC).
- 🧼 Regularly clean your email list.
- ⏱️ Retry sending in case of soft bounces.
- 🧠 Use tools like Sendrella to check bounce risk before delivery.
🧮 Bonus: Bounce Score Concept
Some email tools assign a "bounce score" to help classify emails as:
- Valid
- Risky
- Bounced
These scores help automate rejection of high-risk addresses in signup forms or campaigns.
💡 Final Thoughts
Bounce emails are more than a technical hiccup — they’re a signal. A signal that your data quality, infrastructure, or outreach practices might need work.
Understanding and reducing bounce rates is critical to the success of any email marketing strategy.
Got questions about bounces? Want help cleaning your list? Reach out here.