Email bounces happen when a sent email can't be delivered. High bounce rates damage your sender reputation and can get you blacklisted. Here's how EmailKit helps you reduce bounces.
Your bounce rate is the percentage of emails that fail to deliver out of the total emails you send. For example, if you send 1,000 emails and 50 bounce, your bounce rate is 5%.
A hard bounce means the email permanently failed to deliver. Common causes:
Email doesn't exist — The mailbox was deleted or never existed
Domain doesn't exist — The domain has no DNS records
Blocked by server — The receiving server permanently rejected the email
Impact: Hard bounces are the most damaging. Even a small number can hurt your sender reputation.
What to do: Remove hard-bounced addresses immediately. Never send to them again.
A soft bounce means the email temporarily failed to deliver. Common causes:
Mailbox full — The recipient's inbox is full
Server temporarily down — The mail server is temporarily unavailable
Message too large — The email exceeds the server's size limit
Impact: Soft bounces are less damaging but should still be monitored.
What to do: Retry soft-bounced emails once or twice. If they continue to bounce, remove them.
Bounce Rate | Status | Action |
|---|---|---|
Under 2% | Healthy | Keep verifying regularly |
2% – 5% | Warning | Clean your list before next send |
Over 5% | Critical | Stop sending and clean your list immediately |
Most email service providers (ESPs) will suspend your account if your bounce rate exceeds 5-10%.
By verifying your email list before sending, EmailKit helps you:
Remove undeliverable addresses — These would cause hard bounces
Flag risky addresses — Catch-all domains and disposable emails are more likely to bounce or be problematic
Identify invalid formats — Syntax errors and typos are caught before they reach your ESP
Detect stale addresses — Mailboxes that no longer exist are flagged
Verify before every campaign — Email lists degrade over time. Re-verify lists that are more than a few months old
Verify at point of collection — Use the EmailKit API to verify emails in real-time as users sign up
Remove all "Undeliverable" results — Never send to addresses marked as undeliverable
Review "Risky" addresses — Consider removing disposable and low-quality addresses from marketing campaigns
Handle "Unknown" carefully — These addresses may or may not bounce. Re-verify them before sending
Monitor your sending metrics — Track bounces from your ESP alongside EmailKit verification results
After verifying and cleaning your email list with EmailKit:
Send only to addresses marked as Deliverable
Consider excluding Risky addresses from cold outreach
Keep monitoring your bounce rate after sending
Re-verify your list periodically (monthly for active lists, quarterly for inactive ones)
