Bulk email verifier: real-time email verification with catch-all detection — verify every address before you send.

Live syntax, MX and SMTP checks confirm the mailbox actually exists — not just a static lookup. Catch-all detection runs on every address as well, so accept-all domains are labelled rather than guessed.

Yes — catch-alls are flagged and separated into their own segment so you can decide whether to send.

Yes — upload a whole list and get a cleaned, deduplicated, segmented file back as CSV or XLSX.

Yes — try the free single-email verifier on our Free Tools page first, no login needed. For bulk lists, the free trial includes 50 verification credits with no card.

Yes — upload any list, scraped, purchased or exported, and Coldcast runs live MX and SMTP checks on every address, flags catch-alls, and returns a clean, segmented, send-safe file.

Validation is the cheap part: checking that an address is correctly formatted and that its domain has mail (MX) records. Verification goes further and asks the receiving mail server, over SMTP, whether that specific mailbox exists. Coldcast runs both on every address: syntax and MX validation first, then a live SMTP mailbox check, plus catch-all detection so accept-all domains are labelled instead of guessed.

A catch-all (accept-all) domain is configured to accept mail for any address, so the server says yes even for mailboxes that do not exist. That means an SMTP check alone cannot confirm the person is real. Coldcast flags these addresses and separates them from your valid segment. Send to the valid segment first, and treat the catch-all segment as a separate, smaller send you monitor for bounces, or skip it entirely if deliverability matters more than reach.

Occasionally, yes. Verification confirms the mailbox existed at the moment of the check, but mailboxes get closed, fill up, or sit behind servers that were briefly unreachable. That is why Coldcast runs live checks at verification time rather than reading from a cached database, and why we recommend re-verifying any list that has been sitting for a while before you send to it again.

No. Coldcast checks addresses at the mail-server handshake level: it asks the recipient’s server whether the mailbox exists and then disconnects. No email is sent from your domain during verification, so nothing is delivered, opened or bounced on your behalf. Your reputation only comes into play when you send, which is exactly why you verify first.

1 credit per email checked, at $10 per 10,000 credits. Credits are bought as pay-as-you-go packs that never expire, with no subscription and no per-seat pricing, so you only buy what you need when you have a list to clean. The same credit balance is shared with Coldcast’s scrapers and enrichment.

Paste addresses directly or upload a CSV. Results come back as a clean, deduplicated CSV or Excel (XLSX) file split into valid, risky (catch-all) and invalid, or you can sync them straight to HubSpot, Salesforce, Instantly, Smartlead, Lemlist or Google Sheets.

Valid means the address passed syntax and MX checks and the mail server confirmed the mailbox exists. Invalid means the address is malformed, the domain has no mail records, or the server rejected the mailbox, so it will hard bounce. Risky is where the domain is a catch-all, so the server accepts everything and existence cannot be confirmed by SMTP alone. Each status is exported as its own segment so you decide what to send to.

No. Invalid addresses are exported in their own segment alongside the valid and risky ones, so you can see exactly what was removed and why, keep the row for a re-enrichment pass, or drop it from the campaign entirely.

Yes. Exports are deduplicated, so the same address never appears twice in your valid segment and a contact is not emailed twice because they were on two source lists.

Emails returned by waterfall enrichment are already verified before you are charged, since you only pay when a verified email is found. Lists exported from the Sales Navigator, Apollo or ZoomInfo scrapers, or any list you bring from elsewhere, should be run through Email Verify before they touch a campaign, because database emails go stale and often include catch-alls.

No. The bulk email verifier runs in the Coldcast dashboard: paste or upload a list, download the cleaned CSV or XLSX, or sync it to your sender or CRM. The Coldcast Chrome extension is for the scrapers, not for verification.

Yes. The free trial includes 50 verification credits, plus 100 lead credits and 50 enrichment credits, with no card required. You can also check a single address on the Free Tools page before signing up.