Ask ChatGPT or Claude for someone's work email and you may get one back. It can look perfectly plausible and still not exist. When we tested 9 AI models on this, 76% of the email addresses they came up with were invalid (Hunter's AI email study).
An email verification MCP server lets your AI assistant check an address before you send. We reviewed 8 of them: what their answers include, what else they can do, what they cost, and how they handled 25 email addresses we made up.
What we found:
- 7 of the 8 caught every fake address. Only Kickbox let one through. A free "verifier" that only checks the company's email setup let 24 through.
- Only one tells you where an address was found. If someone replies "how did you get my email?", Hunter's answer includes the pages where the address appears. None of the others do.
- "Can't confirm" is where you can still get caught out. There's a paragraph below you can paste into your assistant so it doesn't treat "can't confirm" as safe.
We ran Hunter, Giggal, and ZeroBounce through their MCP servers. For the other five, we sent the same addresses straight to the checking service their MCP connection uses.
With 7 of the 8 catching every fake, the test alone doesn't pick a winner. We recommend Hunter for two things the others don't do: it shows where each address was found, and it covers finding, checking, and sending in one MCP server. If you mainly clean big lists inside a chat, ZeroBounce or Giggal is the better fit, and Giggal is the cheapest. Yes, Hunter wrote this review. The evidence is below, including where other tools did better.
What is an email verification MCP server?
An email verification MCP server is an add-on that lets ChatGPT, Claude, or another AI assistant check whether an email address can receive mail. It asks the company's mail server whether that inbox exists, without sending anything. In ChatGPT and Claude, you add one as a custom connector, using the web address the vendor gives you. "MCP" stands for Model Context Protocol, the standard that makes this work.
The 8 MCP servers at a glance
MCP server | Works in ChatGPT / Claude in the browser | Checks a whole list in the chat | Shows where the address was found | Also finds and sends emails | Fake addresses let through | Cost per 100 checks |
|---|---|---|---|---|---|---|
Hunter | Yes | No, one at a time | Yes | Yes | 0 of 25 | $1.23 ($1.10 with Data Platform credits) |
ZeroBounce | Through Composio* | Yes | No | Finds only | 0 of 25 | $1.95 |
Giggal | Yes | Yes | No | No | 0 of 25 | $0.17 |
Bouncer | Yes, sign-in only | Yes | No | No | 0 of 25 | $0.60 |
Clearout | Through Composio* | Varies | No | No | 0 of 25 | $0.80 |
Emailable | Through Composio* | Varies | No | No | 0 of 25 | $0.76 |
NeverBounce | Through Composio* | Varies | No | No | 0 of 10 | $0.80 |
Kickbox | Through Pipedream* | Varies | No | No | 1 of 25 | $1.00 |
*Composio and Pipedream are services that host MCP servers for companies that don't make their own. You connect your account with the checker through them.
Test run 8 October 2026, prices checked 22 October 2026.
When someone asks "how did you get my email?"
If you email people who never gave you their address, one of them may ask. Under the EU's GDPR, if you collect someone's personal data from somewhere other than them, you have to be able to tell them where it came from (GDPR Article 14).
A checker that only says "valid" can't help you answer that. Hunter's can. For any address Hunter has seen before, the answer lists the public web pages where it appears, when Hunter first found it there, when it last saw it, and whether it's still on the page.
When we checked press@pipedrive.com, Hunter's answer came back "valid," last verified on 25 September 2026, with 30 sources: Pipedrive's own newsroom and About pages, press releases on Business Wire, and tech news sites. It also showed which of those pages no longer list the address. So your reply can be: "Your address is on your company's newsroom page, where we found it in September 2026."
That's useful for a recruiter writing to one candidate, and for an agency that has to show a client where every contact came from. Legal and procurement teams at large companies can ask the same question before they approve a tool.
It's not limited to verification. Every email address Hunter's MCP server returns comes with the same sources and check date, whether it came from checking an address, finding one person's email, or listing everyone at a company.
The test: 25 made-up addresses
We picked 25 real companies, from IBM and Microsoft to Monzo and Ghost, and invented an address at each one using common formats like firstname.lastname@company.com and names that belong to nobody. Every address is fake, so "valid" is the one wrong answer.
Checker | Checked | Said "valid" (wrong) | Said "invalid" | Said "can't confirm" |
|---|---|---|---|---|
Domain-only check | 25 | 24 | 1 | n/a |
ZeroBounce | 25 | 0 | 23 | 2 |
Giggal | 25 | 0 | 22 | 3 |
Hunter | 25 | 0 | 18 | 7 |
Bouncer | 25 | 0 | 18 | 7 |
Clearout | 25 | 0 | 10 | 15 |
Emailable | 25 | 0 | 9 | 16 |
Kickbox | 25 | 1 | 9 | 15 |
NeverBounce | 10 | 0 | 1 | 9 |
"Can't confirm" covers each tool's own wording: accept all, catch-all, risky, or unknown. Hunter's statuses are Valid, Invalid, Accept all, Disposable, Unknown, and Webmail (what each one means). NeverBounce's free account came with 10 credits, so we ran 10 addresses.
Before anything else: don't let "can't confirm" turn into a send
Some companies set up their email to accept mail for every address, real or not. These are called accept-all (or catch-all) domains. From outside, nobody can tell whether a particular person works there, so a good checker says "can't confirm." Hunter marked its 7 as Accept all, with scores of 73-74 out of 100, and a 73 can look like a pass. The same goes for any checker's "catch-all" or "risky" label.
Paste this into your assistant's custom instructions:
When you check email addresses, only treat "valid" as safe to email. Treat "invalid" and "disposable" as unsafe. Treat "accept all," "catch-all," "risky," and "unknown" as unconfirmed: tell me, and don't count them as safe. Never suggest an email address you haven't checked.
What else the test showed
- A domain-only check isn't verification. It only checks that the company has email, which an invented address at a real company always passes. That's what the most-used verifier on Smithery, a marketplace for these MCP servers, does. We read its code and ran the same checks ourselves.
- Kickbox let one fake through. It marked jzzexample@bmw.de as deliverable, with a high score and no warning.
- The checkers split on "can't confirm." ZeroBounce and Giggal called most of those addresses "invalid." Clearout, Emailable, and Kickbox mostly said "can't confirm." Hunter and Bouncer were in between.
Because every address was fake, the test can't show whether a checker wrongly rejects real people, so a high "invalid" count isn't automatically better. For 5 of Giggal's 22 "invalid" answers, the reason was "mailbox could not be verified," which reads more like "can't confirm."
How we ran it: Hunter and Giggal through their own MCP servers, and ZeroBounce through Composio. Our test ran on API keys, and Bouncer's MCP server only accepts a browser sign-in, so we sent the addresses to its checking service directly. Signing in is still the safer setup for you. NeverBounce, Emailable, Clearout, and Kickbox have no MCP server of their own, so we used the same checking services their Composio or Pipedream connections call. All on free plans.
What each answer includes
Beyond valid, invalid, or can't confirm, the detail in each answer varies.
The answer includes | Hunter | ZeroBounce | Clearout | Emailable | Bouncer | Kickbox | Giggal | NeverBounce |
|---|---|---|---|---|---|---|---|---|
Where the address was found | Yes | No | No | No | No | No | No | No |
Date it was checked | Yes | Yes | Yes | No | No | No | No | No |
Flags generic addresses (info@, support@) | No | Yes | Yes | Yes | Yes | Yes | No | No |
Typo suggestion | No | Yes | Yes | Yes | No | Yes | No | Yes |
Guesses about the person (name, gender, location) | No | Yes | No | Yes | No | No | No | No |
Every checker except Giggal also flags disposable addresses, and all 8 flag accept-all domains.
Hunter doesn't flag generic addresses like info@ or suggest fixes for typos, and several others do. And ZeroBounce and Emailable go the other way, guessing a likely name, gender, and, from ZeroBounce, a city, based on the address. That can save a step. It's also personal data you didn't ask for and can't trace to a source.
What else each MCP server can do
Most of these MCP servers only check addresses. Hunter's covers every step from finding a company to reading the replies. In one chat, you can ask it to use Discover to find software companies in Germany with 50-200 employees, use Domain Search to list their heads of marketing, check their emails with the Email Verifier, save them as Leads, push them to HubSpot, Salesforce, Pipedrive, or Zoho, and start a Sequence. Each step is a tool the MCP server already has.
ZeroBounce's MCP server can also find email addresses. None of the others go beyond checking. If you'd otherwise use a separate tool to find prospects and another to send, that's one account and one set of credits instead of three.
What Hunter doesn't do is check a whole list in one go inside the chat. ZeroBounce and Giggal can, Giggal up to 1,000 addresses per call. For really big lists, Hunter, ZeroBounce, and others offer bulk verification in their web apps.
Which MCP server to choose
If you need to... | Pick | Why |
|---|---|---|
Know where every address came from | Hunter | The only MCP server we reviewed that lists the pages where each address was found, with dates |
Find, verify, and send from one chat | Hunter | The only one here that covers every step, from finding companies to reading replies |
Check one candidate's or prospect's email before reaching out | Hunter | Works in the browser on the Free plan, and shows where the address was found if they ask |
Show clients where every contact came from (agencies) | Hunter | Each address comes with its sources and check date |
Clean a whole list inside the chat | ZeroBounce or Giggal | Both check a list in one call. Giggal is the cheapest checker we reviewed. |
Get the firmest answer on accept-all domains | ZeroBounce or Giggal | They called the most fakes "invalid" (23 and 22). Check their reasons. |
Keep a checker you already pay for | NeverBounce, Clearout, Emailable, or Kickbox through Composio | No need to switch |
Our default is Hunter. If your outreach involves more than checking an address (finding people, writing to them, and following up), Hunter's MCP server does all of that, and its find rate is strong. In Hunter's AI email study, it returned an email for 73% of 305 people we asked about, and 64% of the 305 were verified deliverable. The best AI model on its own managed 20%.
Avoid: free community "verifiers" that only check the company's email setup. In our test, that approach let 24 of 25 invented addresses through.
What it costs
Prices from each vendor's own pricing page, checked on 22 October 2026. "Smallest purchase" is the least you can spend to get started. "Lowest price" is the best rate they publish, which needs a big pack or plan.
Checker | Smallest purchase | Lowest price per 100 verifications | Cheapest way to buy |
|---|---|---|---|
Giggal | $5 for 3,000 | $0.07 (1 million for $680) | Credit packs |
Clearout | $8 for 1,000 | $0.08 (1 million a month, $800 a month billed yearly) | Yearly subscription |
NeverBounce | $8 for 1,000 | $0.10 (1 million a month, $999 a month) | Monthly subscription, which also includes other tools |
Bouncer | $6 a month for 1,000 | $0.16 (1 million a month, $1,600 a month) | Monthly subscription |
Emailable | $38 for 5,000 | $0.18 (1 million a month, $1,785 a month) | Monthly subscription |
ZeroBounce | $39 for 2,000 | $0.20 (1 million a month, $1,999 a month billed yearly) | Yearly subscription, which also includes other tools |
Kickbox | $5 for 500 | $0.30 (1 million for $2,999) | Credit packs |
Hunter (Data Platform credits) | $11 for 1,000 | $0.28 (1 million for $2,800) | Credit packs |
Hunter (Starter, Growth, Scale plans) | $49 a month for up to 4,000 (Starter) | $0.42 (Scale, billed yearly) | Yearly plan, which also includes finding emails, enrichment, and Sequences |
On Hunter's plans, one verification costs half a credit, and the same credits also pay for finding emails and enrichment. The plan figures assume you spend all your credits on verification.
If checking addresses is all you need, Giggal is the cheapest at every size. Hunter's plans also include finding emails, company and person lookups, saving Leads, and sending Sequences, so if you'd otherwise pay for a separate finder and a separate sending tool, the price per verification isn't the whole comparison.
Before you connect any of them
- Use the vendor's own MCP server, and sign in rather than pasting a key. In 2025, a fake version of a popular email MCP server was caught secretly copying every email it sent to a stranger. It was downloaded about 1,600 times before it was pulled (The Hacker News). If you send anything confidential, like candidate names or client details, that's not a risk worth taking.
- Check whether it works in your browser. ZeroBounce's own MCP server has to be installed on your computer, so in ChatGPT or Claude on the web you'd need Composio in between.
How to add Hunter's MCP server to ChatGPT or Claude
Hunter also has ready-made apps for ChatGPT, Claude, and Gemini, but we recommend adding the MCP server itself. It gives your assistant access to the full Hunter platform, including everything covered in this review. It takes a couple of minutes and there's nothing to install.
In Claude:
- Open Settings → Connectors and click Add custom connector.
- Paste https://mcp.hunter.io/mcp and give it a name, like "Hunter."
- Sign in to your Hunter account when asked.
- In a new chat, ask: "Check whether this email is real: [address]. Show me where it was found."
In ChatGPT:
- Open Settings → Apps & Connectors and turn on developer mode under Advanced.
- Create a new connector and paste https://mcp.hunter.io/mcp.
- Sign in to your Hunter account when asked.
- Ask the same question.
In other AI tools: any assistant that supports MCP servers can use the same address.
Then paste the "can't confirm" instruction above into your assistant's custom instructions.
→ Get started with Hunter's MCP server. The Free plan works.
For your tech person: Hunter's MCP server is at https://mcp.hunter.io/mcp and accepts OAuth or an X-API-Key header. Full details in the MCP setup docs.
FAQ
What's the best MCP server for email verification?
It depends on what you need. Hunter is our default: it's the only MCP server we reviewed that shows where each address was found, and it covers finding, verifying, and sending in one place. For cleaning big lists inside a chat, ZeroBounce and Giggal are the better fit.
Which email verifier is most accurate?
Our test can't say, because it only used made-up addresses. It shows that a domain-only check passed 24 of 25 fakes, Kickbox passed 1, and Hunter, ZeroBounce, Giggal, Bouncer, Clearout, Emailable, and NeverBounce passed none.
Can I check a candidate's email before reaching out?
Yes. With a verification MCP server in ChatGPT or Claude, paste the address and ask whether it's valid. With Hunter's, you can also ask where the address was found, so you have an answer if the candidate asks how you got it.
Can ChatGPT or Claude check an email address on its own?
No. An AI model can't contact a mail server, so it can only guess. In Hunter's study, 76% of the addresses AI models produced were invalid. To check an address, the assistant needs a verification MCP server.
Does checking an email send a message to that person?
No. A verifier asks the company's mail server whether the inbox exists and stops there. Nothing arrives in anyone's inbox.
Why does it matter where an email address was found?
If someone asks how you got their address, you need an answer, and under GDPR you may be required to give one. Hunter's MCP server lists the public pages where each address appears, with dates. None of the other checkers we reviewed do.
What should I do with email addresses ChatGPT already gave me?
Check them before you send. With a verification MCP server, you can paste them into the same chat and ask which ones are valid. Treat anything that comes back "accept all," "catch-all," or "risky" as unconfirmed.
Can I verify a whole list in ChatGPT?
With ZeroBounce's or Giggal's MCP server, yes. Hunter's MCP server checks one address at a time. For hundreds of addresses, bulk verification in the vendor's web app is the better tool.
Does it cost extra?
Checks use the same credits as each company's regular service, so there's no extra charge for the MCP server. On the cheapest paid options, 100 checks cost from $0.17 (Giggal) to $1.95 (ZeroBounce). Hunter is $1.23 on its Starter plan, which also covers finding emails, lookups, and sending, or $1.10 with Data Platform credits.
Send cold emails with Hunter