StopBouncingBulk Email Verification.
Upload. Verify. Download.
Upload your email list as a CSV and get verified results in minutes. Remove invalid, disposable, and unverifiable addresses before they damage your sender reputation.
100 free credits on signup. No credit card required.
Three Steps to a Clean Email List
Upload your list
Drag and drop any CSV file. Our parser automatically detects the email column — no specific formatting required. Supports files up to hundreds of thousands of addresses.
Verification runs automatically
Every address passes through syntax, DNS, MX, SMTP, disposable, catch-all, and role checks concurrently. Most lists process at thousands of verifications per minute.
Download your clean list
Results are added as a new column in your CSV. Filter by status — Valid, Invalid, Unknown, Disposable — and download exactly the segment you need.
Built for Marketing Teams and Developers
Any CSV format
No special formatting required. Upload exports from Mailchimp, HubSpot, Salesforce, Klaviyo, or any other platform.
Fast processing
Most lists process in minutes, not hours. Our parallel verification engine handles high volumes efficiently.
Secure & GDPR-compliant
All data is encrypted in transit and at rest. Uploaded lists are cleared immediately after processing; results are available for 7 days then permanently deleted. EU-hosted infrastructure.
Accurate results
Over 98% accuracy on clearly valid and invalid addresses. Catch-all domains are honestly flagged as Unknown rather than guessed.
Works With Every Platform Export
Upload exports directly from your marketing platform — no reformatting needed.
How to Use Your Results
Every verified address gets one of four statuses. Here is what to do with each.
| Status | Action |
|---|---|
| Valid | Send |
| Invalid | Remove immediately |
| Unknown | Send with caution |
| Disposable | Remove or flag |
When to Run Bulk Verification
Before a major campaign
Verify the full send list before any large batch. One pass catches invalid addresses accumulated since your last send.
After importing contacts
Any import from a CRM, event export, or third-party source introduces unknown-quality addresses. Verify before sending to any imported segment.
Quarterly list hygiene
Even actively-mailed lists degrade. Addresses go stale as people change jobs and companies shut down. A quarterly pass keeps bounce rates consistently low.
Before platform migration
Migrating ESPs with a dirty list risks triggering spam filters on the new platform. Verify and clean before importing to your new sending service.
Re-engaging a dormant list
Lists that haven't been mailed in 6+ months have the highest bounce rates. Always verify before re-engaging — the decay is significant.
After list growth spurt
Rapid list growth from a giveaway, event, or paid campaign often includes low-quality addresses. Verify new additions before mixing them into your main list.
Bulk Verification FAQ
How large a file can I upload?
StopBouncing supports CSV files with hundreds of thousands of email addresses. If you need to verify millions of addresses, use our API to integrate verification directly into your data pipeline without file size limits.
How long does bulk verification take?
Processing time depends on list size and the domains involved. A list of 10,000 emails typically takes 15–30 minutes. Some mail servers respond slowly, and deliberate SMTP pacing prevents triggering spam filters on destination servers. Very large lists scale proportionally — progress is visible in your dashboard throughout.
Can I upload a list without a header row?
Yes. If your CSV has no header, our system detects the email column based on content patterns. We recommend including a header row for clarity when using exported files from marketing platforms.
How much does bulk email verification cost?
Bulk verification uses the same per-email credit pricing as single lookups — from €0.0006 per address. There are no additional bulk processing fees. You only pay for addresses actually verified, and your credits never expire.
Is my email list kept private?
Yes. Your data is encrypted in transit using TLS and at rest using AES-256. Uploaded lists are cleared immediately after processing completes; verification results are available for 7 days then permanently deleted. We never share, sell, or use customer data for any purpose other than providing the verification service.
What should I do with Unknown results?
Unknown addresses come from catch-all domains — servers that accept all email regardless of whether the specific mailbox exists. They're not confirmed valid or invalid. For marketing, you can include them but set up automatic suppression on the first hard bounce. For high-risk contexts like free trial signups, block or require double opt-in.
Can I re-verify a list?
Yes. You can upload the same list again at any time. Re-verification is useful if significant time has passed since the last check — email addresses decay at roughly 20–30% per year, so a list verified 6 months ago may have meaningful new invalids.
Does bulk verification work for B2B lists?
Yes, but B2B lists have some nuances. Many corporate domains use catch-all configurations, which means individual mailboxes can't be confirmed via SMTP. These are returned as Unknown. For B2B outreach, treat Unknown addresses as risky but not unusable — test with a small segment first and watch your bounce rate.
Ready to Clean Your List?
Upload your first CSV for free. 100 credits included with every new account.