How we verify 500 million emails (and why most “verified” lists aren’t)
May 28, 2026 · 7 min read · The LeadsTitan team
“Verified” is the most overused word in the lead-data business. Almost every provider stamps it on their export. Almost none of them will tell you what it means — because for most, it means “this string contains an @ sign and a domain that resolves.” That’s not verification. That’s spell-check.
Here’s what we actually do before an email earns the Valid badge in a search result.
Stage 1 — Syntax and domain
The cheap checks come first because they eliminate the most records for the least effort. We validate the address against the real RFC rules (not a naive regex), confirm the domain has live MX records, and reject role addresses and disposable domains that will never belong to a buyer.
Stage 2 — Catch-all detection
This is where most “verified” lists quietly fall apart. A catch-all domain accepts mail
to any address — [email protected] included. A lazy verifier pings the
server, sees “accepted,” and marks every address valid. We detect catch-all domains
explicitly and down-rank addresses on them to Risky, because acceptance tells you
nothing about whether a human reads that inbox.
Stage 3 — SMTP probing
For non-catch-all domains we open a conversation with the receiving mail server and ask, politely, whether the specific mailbox exists — without ever sending a message. The response separates a real mailbox from a typo or a former employee.
The goal isn’t to prove an email is perfect. It’s to be honest about our confidence — Valid, Risky, or Unknown — so you decide what to do with it.
Stage 4 — The decay curve nobody talks about
Here’s the part the industry buries: email data rots. People change jobs, companies fold, addresses get retired. A list verified once and sold for two years is mostly fiction by the end.
So verification isn’t a one-time gate for us — it’s a loop. Every record carries a freshness signal, and addresses are re-checked on a rolling schedule. When you reveal a contact today, you’re getting a recent result, not a two-year-old guess.
What this means for you
- You see a deliverability status on every email, not a blanket “verified.”
- Risky and Unknown are surfaced honestly instead of being passed off as valid.
- You spend a credit on a reveal knowing the data behind it was checked recently.
Precision over volume — even when the precision is just being honest about what we don’t know.