What is Bounce Rate?
Email bounce rate is the percentage of sent emails that failed to reach the recipient's inbox.
When an email "bounces," it means the message was returned undelivered. The recipient never received it, and you're notified of the failure.
Bounce Rate Formula:
(Bounced Emails / Total Emails Sent) × 100 = Bounce Rate
Example:
You send 1,000 emails. 30 bounce.
(30 / 1,000) × 100 = 3% bounce rate
A healthy bounce rate is under 2%. Anything above 5% signals serious deliverability problems.
Types of Bounces
Hard Bounces
Permanent delivery failures. The email will never be delivered.
Causes:
- Invalid email address (typos, fake addresses)
- Non-existent domain (company went out of business)
- Recipient mail server doesn't exist
Remove hard-bounced emails immediately. Never email them again.
Soft Bounces
Temporary delivery failures. Might succeed if retried.
Causes:
- Recipient inbox is full
- Recipient mail server is down
- Email file too large
- Recipient's server is blocking temporarily
Retry 1-2 more times over 2-3 days. If still bouncing, remove.
Why Bounce Rate Matters
Deliverability Impact
High bounce rates destroy sender reputation.
The Impact Cycle:
- High bounce rate triggers spam filters
- More emails sent to spam folders
- Lower engagement rates
- Worse sender reputation
- Even more emails blocked
Blacklist Risk
Bounce rates above 5% often trigger blacklisting.
Blacklist Thresholds:
- 5% bounce rate: Risk zone
- 10% bounce rate: Likely blacklisting
- Sustained high bounces: Permanent reputation damage
Wasted Resources
Bounced emails cost money without results.
Cost of Bounces:
- Email platform fees
- Sales rep time spent on bad leads
- List acquisition costs
- Opportunity cost (could have emailed good leads)
Bounce Rate Benchmarks
By Email Type
| Email Type | Excellent | Good | Warning | Critical |
|---|---|---|---|---|
| Cold Email | <0.5% | 0.5-1% | 1-2% | >2% |
| Newsletter | <0.5% | 0.5-1% | 1-2% | >2% |
| Marketing Email | <0.5% | 0.5-1% | 1-2% | >2% |
| Transactional | <0.1% | 0.1-0.5% | 0.5-1% | >1% |
By List Source
| List Source | Typical Bounce Rate |
|---|---|
| Opt-in subscribers | <0.5% |
| Purchased lists | 10-50% |
| Scraped lists | 30-70% |
| Verified prospects | 1-3% |
| Cold outreach (new domains) | 2-5% initially |
Industry Benchmarks
According to Mailchimp and other ESPs:
- Average across all industries: 0.5-2%
- B2B email: 0.7-2.2%
- B2C email: 0.4-1.8%
- Software/SaaS: 0.6-1.5%
Reducing Bounce Rate
Email Verification
Validate emails before sending.
Verification Tools:
- NeverBounce
- ZeroBounce
- Hunter.io Email Verifier
- Bouncer
- Debounce
- Collect email addresses
- Run through verification tool
- Remove invalid addresses
- Send only to verified emails
List Hygiene
Regular cleaning maintains list health.
Hygiene Practices:
- Remove hard bounces immediately
- Remove soft bounces after 3 failures
- Suppress unengaged subscribers (6+ months)
- Scrub role addresses (info@, admin@, support@)
- Remove duplicates and syntax errors
Double Opt-In
For marketing lists, require confirmation.
Double Opt-In Process:
- User subscribes
- Send confirmation email
- User clicks confirmation link
- Add to active list
Warm-Up Properly
New domains need gradual sending increases.
Warm-Up Schedule:
- Week 1: 10-20 emails/day
- Week 2: 20-40 emails/day
- Week 3: 40-70 emails/day
- Week 4+: 70-100 emails/day
Avoid Buying Lists
Purchased lists have terrible bounce rates.
Purchased List Reality:
- 10-30% invalid addresses
- Many spam traps
- Never opted in to hear from you
- Illegal in many jurisdictions (GDPR)
Monitoring Bounce Rate
Daily Monitoring
Check bounce rates daily during active campaigns.
What to Track:
- Overall bounce rate
- Hard vs. soft bounces
- Bounce by campaign/list
- Bouncing domains (specific companies)
Immediate Action
Act fast when bounce rate spikes.
Spike Response:
- Pause sending immediately
- Identify cause (check bounces)
- Remove problematic emails
- Verify remaining list
- Resume at lower volume
Regular Audits
Deep-dive into bounce data monthly.
Audit Checklist:
- Total bounce rate trend
- Hard vs. soft bounce ratio
- Domains with most bounces
- Campaigns with highest bounces
- Recent acquisitions performing poorly
Common Bounce Rate Mistakes
Ignoring hard bounces:
Every hard bounce should be removed immediately. Continuing to email guarantees blacklisting.
Not verifying new lists:
Sending to unverified lists guarantees 5-20% bounce rates. Verification is non-negotiable.
Buying email lists:
Purchased lists have 10-50% bounce rates plus legal risks. Never worth it.
Ramping volume too fast:
New domains sending 500 emails on day one will see high bounces and spam filtering.
Neglecting list cleaning:
Lists decay 2-3% monthly. Clean quarterly or you'll see rising bounces.
Ignoring soft bounces:
Soft bounces that persist after 2-3 attempts are effectively hard bounces. Remove them.
Not segmenting by engagement:
Emailing non-engagers for 6+ months increases bounces as emails go abandoned.
Key Takeaways
- Bounce rate = percentage of emails that fail to deliver
- Healthy bounce rate: under 2%; above 5% is dangerous
- Hard bounces = permanent failures (invalid emails); remove immediately
- Soft bounces = temporary failures (full inbox, server down); retry 2-3 times
- High bounce rates destroy sender reputation and trigger blacklisting
- Reduce bounces by: email verification, list hygiene, double opt-in, proper warm-up
- Never buy email lists—10-50% bounce rates plus legal risk
- Monitor bounce rates daily during campaigns, audit monthly
- Remove hard bounces immediately; soft bounces after 3 failed attempts
- Lists decay 2-3% monthly—clean regularly
- Verification costs $0.003-$0.01 per email; saves 10-100x in deliverability
Sources:
Related Terms
B2B (Business to Business)
Transactions between two businesses, not between business and consumer.
B2C (Business to Consumer)
Transactions between business and individual consumers.
Backlink Outreach
Cold email strategy targeting websites for link-building opportunities.
Bad Lead
Prospect unlikely to convert due to budget, authority, need, or timing misalignment.
