Definition
Bounce rate measures the percentage of emails that could not be delivered because the receiving server rejected them. Bounces fall into two categories that require different responses.
Hard bounces occur when the email address is invalid, does not exist, or the domain is not configured to receive email. These addresses should be removed from your list immediately. Soft bounces occur when the email address is temporarily unreachable due to a full inbox, server timeout, or out-of-office auto-reply.
Formula
Bounce rate is calculated using total bounces (hard + soft) divided by total emails sent.
Bounce Rate = (Total Bounces / Total Emails Sent) × 100
| Variable | Description |
|---|---|
| Total Bounces | Hard bounces + soft bounces |
| Total Emails Sent | Number of emails you attempted to send |
Average Benchmark
| Bounce Type | Acceptable Rate |
|---|---|
| Total bounce rate | Below 3% |
| Hard bounce rate | Below 1% |
| Soft bounce rate | Below 2% |
A total bounce rate above 5% indicates list quality issues. If your hard bounce rate exceeds 2%, mailbox providers may flag your sending reputation.
How to Improve Bounce Rate
- Use double opt-in: Confirmed opt-in ensures every subscriber entered a valid email address before joining your list.
- Validate emails at point of capture: Use real-time email validation to catch typos, invalid domains, and disposable email addresses during sign-up.
- Remove hard bounces immediately: Never retry sending to an address that hard bounced. Most email platforms automatically suppress hard bounces.
- Handle soft bounces with limits: Retry soft bounces 2-3 times over several days. If an address soft bounces consistently across multiple campaigns, move it to a suppression list.
- Monitor for role-based addresses: Addresses like admin@, info@, or support@ have higher bounce rates. Consider excluding them from acquisition.
- Prune engaged segments quarterly: Pull a list of subscribers who have not opened or clicked in 180 days and gradually remove them.
Example Calculation
If you send a campaign to 15,000 subscribers and receive 135 hard bounces and 210 soft bounces:
Total Bounces = 135 + 210 = 345
Bounce Rate = (345 / 15,000) × 100 = 2.3%
A total bounce rate of 2.3% is within the acceptable range. The hard bounce rate component (135/15,000 = 0.9%) is also below the 1% threshold.
Related Glossary Terms
A/B Testing
A/B testing in email marketing is the practice of sending two variations of an email to a small sample of your list to determine which version performs better before sending the winner to the remaining subscribers.
Abandoned Cart Email
An abandoned cart email is an automated message sent to customers who added items to their online shopping cart but left without completing the purchase. It is one of the highest-converting email types in ecommerce.
Abuse Complaint
An abuse complaint is a report from a recipient who marks an email as spam, which negatively affects sender reputation and deliverability.
Alt Text
Alt text is the written alternative to an image in an email, displayed when images are blocked, slow to load, or consumed by screen readers.
AOL Mail for Email Marketers
AOL Mail is a legacy email provider with specific deliverability requirements and rendering quirks, now operating as part of the Yahoo+AOL network under shared infrastructure.
ARPU (Average Revenue Per User)
ARPU (Average Revenue Per User) is a metric that measures the average revenue generated per email subscriber over a specific period, used to evaluate list value and campaign effectiveness.
Frequently Asked Questions
A hard bounce means the email address is permanently invalid — the address does not exist, the domain is wrong, or the mail server rejects all mail. Hard bounces should be removed immediately. A soft bounce means the email was temporarily undeliverable — the inbox is full, the server is down, or the message was too large. Soft bounces can be retried later.
A healthy email list should have a bounce rate below 3%. Hard bounce rates should stay below 1%. If your bounce rate exceeds 5%, your list acquisition or hygiene process needs attention. High bounce rates damage sender reputation with email providers.
Yes, especially hard bounces. Sending to too many invalid addresses signals to mailbox providers that you do not maintain your list, which can hurt your sender reputation and inbox placement. The effect is more significant on shared IPs where your reputation is also influenced by other senders.
The most common causes are purchased or scraped email lists, signup forms without verification, outdated contact databases, and typos at the point of collection. Regular list hygiene and double opt-in verification can prevent most of these issues before they damage your sender reputation.
Use double opt-in to verify email addresses at signup. Remove hard bounces immediately and soft bounces after three failed attempts. Use an email verification service to clean your existing list. Never buy email lists — they are the leading cause of high bounce rates and deliverability problems.