The email verifier — check deliverability before you send
WarmySender's email verifier checks whether an address is safe to send to before you hit send. Every address you check comes back as one of four clear results — valid, invalid, risky, or unknown — and the verifier includes catch-all detection so you know when a domain accepts everything and can't be confirmed one address at a time. Verify every address on your list to protect your sender reputation and keep bounce rates low, so the mailboxes you've warmed up keep landing in the inbox.
The verifier is built into the same platform you use to find prospects and reach them across all four pillars — Cold Emailing, Email Warmup, LinkedIn Outreach, and Multichannel sequences. Clean your list, warm up your mailboxes, and send — all from one dashboard, starting at $14.99/month.
What it is
The email verifier is a deliverability check you run on your prospect list before you send. Instead of finding out an address was bad after a bounce has already hurt your reputation, you find out first. Upload or select a list, and the verifier tells you which addresses are safe to send to, which to remove, and which to treat with care — one clear result per address.
The four statuses
Every address you verify comes back as exactly one of these:
| Status | What it means | What to do |
|---|---|---|
| Valid | The address exists and can receive mail. Safe to send. | Send with confidence. |
| Invalid | The address doesn't exist or can't receive mail. Sending would bounce. | Remove it — don't send. |
| Risky | The address may accept mail but carries a higher chance of a bounce or complaint (for example, a catch-all domain or a role address). | Send with care, or set aside for a warmed-up mailbox. |
| Unknown | A confident result couldn't be reached this time — the receiving side didn't give a clear answer. | Re-check later, or send cautiously with warmup running. |
Catch-all detection explained
Some domains are configured to accept mail sent to any address at that domain, whether or not the specific mailbox exists. These are called catch-all domains. On a catch-all domain, an individual address can't be confirmed to exist one at a time — the domain would say "yes" to almost anything — so the honest result is that the address is riskier than a normally-confirmable one.
The verifier detects catch-all domains and flags the affected addresses so you're not misled into treating "the domain accepts mail" as "this exact person exists." That lets you decide deliberately: send to catch-all addresses through a well-warmed mailbox, hold them back, or prioritize your confirmed-valid contacts first.
Why verify before sending
Bounces wreck domain reputation. When you send to addresses that don't exist, mailbox providers see a spike in bounces and start treating your domain as a low-quality sender — which pushes even your good mail toward spam. Verifying first breaks that cycle:
- Protect sender reputation. Removing invalid addresses before you send keeps your bounce rate low and your domain trusted.
- Keep bounce rates low. A clean list means more of your emails reach the inbox and fewer get filtered.
- Protect the work you put into warmup. Warmup builds your reputation up; a batch of bounces can tear it down. Verifying keeps the two working together.
Verification credits
Every paid plan (Pro and up) includes the email verifier. When you need to verify more than your plan covers, you can top up with one-time verification credits:
- Credits never expire. A one-time pack stays on your account until you use it — no monthly reset, nothing lost if you don't use it all at once.
- One credit per confirmed address. A credit is spent when an address comes back with a confident result (valid, invalid, or risky). Unknown results don't cost a credit.
- Verify a big list right away. Credits let you clear a large list in one pass instead of waiting, while checks still run at a steady, safe pace for accuracy.
See the pricing page for current plans and verification-credit packs.
How it fits — verify, warm up, send
The verifier is one step in a deliverability-first workflow that runs entirely inside WarmySender:
- Verify. Check your list so you keep only addresses that are safe to send to, and flag the risky ones.
- Warm up. Keep email warmup running on your mailboxes so they build and hold a strong sender reputation.
- Send. Launch your cold email campaign to a clean list from a warmed-up mailbox — the combination that lands in the inbox.
Your leads can come straight from the built-in B2B lead database, so you can find prospects, verify them, warm up, and send without ever leaving the platform.
Frequently asked questions
What do valid, invalid, risky, and unknown mean?
Every address you verify comes back as exactly one of four results. Valid means the address exists and can receive mail — safe to send. Invalid means it doesn't exist or can't receive mail — remove it. Risky means it may accept mail but has a higher chance of a bounce or complaint (for example a catch-all domain) — send with care. Unknown means a confident answer couldn't be reached this time — re-check later or send cautiously with warmup running.
What is a catch-all domain?
A catch-all domain is set up to accept mail sent to any address at that domain, whether or not the specific mailbox exists. Because the domain would accept almost anything, an individual address on it can't be confirmed one at a time, so it's flagged as riskier. The verifier detects catch-all domains so you can decide whether to send to those addresses through a well-warmed mailbox or hold them back.
Why verify before sending?
Sending to addresses that don't exist causes bounces, and bounces wreck your domain's reputation with mailbox providers — which pushes even your good mail toward spam. Verifying first lets you remove invalid addresses before they ever cost you, keeping your bounce rate low, your reputation intact, and more of your emails in the inbox.
Do verification credits expire?
No. The email verifier is included on every paid plan, and if you top up with one-time verification credits, those credits never expire — they stay on your account until you use them. One credit is spent per confirmed result (valid, invalid, or risky); unknown results don't cost a credit.
Can an AI agent verify emails via API?
Yes. WarmySender offers a public REST API and an MCP server, so an AI agent (such as Claude or ChatGPT) can verify email addresses for you and act on the results — the same verification you'd run in the app, driven by your assistant in plain language.
How does the verifier fit with warmup and campaigns?
It's the first step in a deliverability-first workflow: verify your list to keep only safe-to-send addresses, keep email warmup running so your mailboxes hold a strong reputation, then send your campaign from a warmed-up mailbox to a clean list. Your leads can come straight from the built-in lead database, so the whole flow — find, verify, warm up, send — happens in one place.
Ready to clean your list?
Open the Email Verifier, check your list, and send only to addresses that are safe — then keep warmup running and launch with confidence, all from one dashboard.
- What your verification results mean — a deeper look at valid, invalid, risky, and unknown
- B2B lead database — find prospects, then verify them before you send
- Pricing — current plans and verification-credit packs