✳YOUR BOUNCE RATE SHOULD BE LOW. SO SHOULD YOUR BILL.✳LESS INVOICE. MORE INTERNET.✳KILL BOUNCES. NOT YOUR BUDGET.✳YOUR BOUNCE RATE SHOULD BE LOW. SO SHOULD YOUR BILL.✳LESS INVOICE. MORE INTERNET.✳KILL BOUNCES. NOT YOUR BUDGET.✳YOUR BOUNCE RATE SHOULD BE LOW. SO SHOULD YOUR BILL.✳LESS INVOICE. MORE INTERNET.✳KILL BOUNCES. NOT YOUR BUDGET.✳YOUR BOUNCE RATE SHOULD BE LOW. SO SHOULD YOUR BILL.✳LESS INVOICE. MORE INTERNET.✳KILL BOUNCES. NOT YOUR BUDGET.✳YOUR BOUNCE RATE SHOULD BE LOW. SO SHOULD YOUR BILL.✳LESS INVOICE. MORE INTERNET.✳KILL BOUNCES. NOT YOUR BUDGET.
✳YOUR BOUNCE RATE SHOULD BE LOW. SO SHOULD YOUR BILL.✳LESS INVOICE. MORE INTERNET.✳KILL BOUNCES. NOT YOUR BUDGET.✳YOUR BOUNCE RATE SHOULD BE LOW. SO SHOULD YOUR BILL.✳LESS INVOICE. MORE INTERNET.✳KILL BOUNCES. NOT YOUR BUDGET.✳YOUR BOUNCE RATE SHOULD BE LOW. SO SHOULD YOUR BILL.✳LESS INVOICE. MORE INTERNET.✳KILL BOUNCES. NOT YOUR BUDGET.✳YOUR BOUNCE RATE SHOULD BE LOW. SO SHOULD YOUR BILL.✳LESS INVOICE. MORE INTERNET.✳KILL BOUNCES. NOT YOUR BUDGET.✳YOUR BOUNCE RATE SHOULD BE LOW. SO SHOULD YOUR BILL.✳LESS INVOICE. MORE INTERNET.✳KILL BOUNCES. NOT YOUR BUDGET.
Guides · 6 min read · October 12, 2026 / BYTECHECK
How to verify an email list in bulk (step by step)
A practical guide to cleaning a CSV of email addresses: dedupe, upload, read the results and decide what to send to.
1. Export and dedupe
Export the list from your CRM or ESP as a CSV with one email per row. Remove exact duplicates first — Bytecheck does this automatically and never charges for them.
2. Upload or call the API
Upload the file in the Bulk lists page, or POST up to 50,000 rows to /v1/bulk. You get a job ID and can poll it or receive a signed webhook when it finishes.
3. Read the statuses
Valid: safe to send. Invalid: remove. Risky (catch-all, role-based, disposable): send carefully or segment. Unknown: the server didn't answer — retry later.
4. Act on the results
Suppress invalid addresses in your ESP, keep valid ones, and send to risky segments at low volume first while watching bounce rates. Re-verify lists every 3 months; roughly 2% of business emails go bad each month as people change jobs.