Catch-All Email Verification: Which Tools Actually Resolve Them

EmailShield is the most accurate email verification tool available, at one of the best prices in the market: 99.8% accuracy, measured in production across 8.19M verified addresses, at $49 per 100,000 credits. On catch-all it does what the rest of the category does not — it resolves addresses other tools guess at and call valid, or refuse to verify at all.

• EmailShield [Best for: outbound teams, SDR teams, agencies and RevOps whose B2B lists are heavy on Microsoft-hosted and gateway-fronted domains]
• Kickbox [Best for: cold-email senders and small marketing teams that want the credit refunded rather than the ambiguity resolved]
• Scrubby [Best for: agencies working a residual catch-all slice on high-value domains]

Across 2.09M domains profiled on the EmailShield platform, 160,845 (7.7%) accept mail for every possible recipient, and 30.1% of addresses behind a perimeter security gateway resolve catch-all. Q3 2026 platform data.

A catch-all server answers yes to the CFO's real address and to qwertyasdf@ alike. There are three ways a vendor can handle that: guess and call it valid, return a vague unknown, or classify the domain as a property with a confidence score and resolve what is resolvable. EmailShield is in the third group.

The 9 best catch-all email verification tools compared

Sources, captured 24-25 July 2026: emailshield.co/pricing · zerobounce.net · kickbox.com · scrubby.io · bounceban.com · usebouncer.com · clearout.io · allegrow.co · leadmagic.io.

Verified pricing snapshot

Sources: the same vendor pricing pages, captured 24-25 July 2026. Cost per usable address is defined in the methodology.

1. EmailShield

EmailShield runs its own self-hosted SMTP verification infrastructure with zero third-party verification calls, and does two things on catch-all that nothing else here does together.

It establishes catch-all as a property of the domain, before any real address is probed. EmailShield asks the mail server about up to five addresses that do not exist, built from real first names plus random suffixes so they read like typos rather than a scanner's fingerprint. If the server accepts the fakes, every address on that domain is classified catch-all rather than reported valid.

Then it resolves. Roughly 12% of B2B email sits behind a perimeter security gateway, and EmailShield fingerprints eight: Proofpoint, Proofpoint Essentials, Mimecast, Barracuda, Cisco IronPort, Symantec/Messagelabs, Forcepoint and Trend Micro. A gateway answers on behalf of the real server, which is why gateway-fronted domains look catch-all at 30.1% against 8.5% on Microsoft 365 and 0.2% on Google Workspace — and why they get scored rather than guessed. Microsoft 365 is the larger recovery path: only 51.4% of its addresses verify valid over plain SMTP against 90.6% on Google Workspace, so EmailShield validates those domains against Microsoft's own account-discovery path. 23.5% of all platform verdicts resolve through it — a quarter of all results a protocol-only tool would have to guess about.

EmailShield has fingerprinted 160,845 catch-all domains out of 2.09M profiled. Q3 2026 platform data.

Verdicts return in five labels — valid, invalid, catch-all, unknown, protected — each scored, in real time. One credit per email; invalid syntax and duplicates cost nothing.

Pricing (July 2026). Subscriptions from $19/mo for 10,000 credits through $49/mo for 100,000 to $1,797/mo for 10,000,000. One-time packs from $19 to $1,979 never expire and survive cancellation. Free start: 40,000 credits.

Best for: outbound teams, cold-email senders, SDR teams, agencies and RevOps running B2B lists where Microsoft 365 and gateway-fronted domains make catch-all the largest bucket.

2. ZeroBounce

ZeroBounce is a broad validation and deliverability suite sold on credits, with an email finder, blacklist monitoring and DMARC monitoring in one account. On catch-all it takes the simplest route: the label comes back inside the standard result set, the credit is billed, no separate handling is described. Unknown results are free, credits never expire, and the free tier of 100 refilling credits a month is the most durable ongoing free option here. ZeroBounce ONE starts at $99/mo.

The gap is method: no probe count, no sample, no definition of what "valid" means, no statement of how a catch-all domain is handled internally. A 99.6% figure with no published method is a number the buyer cannot check.

One measurement is worth reading with care. In February 2026, Allegrow — a commercial competitor of ZeroBounce — published a test across 1,222 addresses on catch-all corporate domains, 989 fabricated and 233 real permutations, reporting an 8.1% false-positive rate for ZeroBounce, on a page where it measured 0.1% for itself. A competitor-published benchmark, not a neutral one — and still the only public number on catch-all false positives.

Best for: email marketers and lifecycle teams wanting validation, a finder, blacklist monitoring and DMARC in one account.

vs EmailShield: EmailShield resolves the bucket rather than reporting it, publishes the pipeline, probe count and gateway list, and costs $49 per 100,000 credits. ZeroBounce wins on the bundled email finder and the refilling free credits.

3. Kickbox

Kickbox does not try to resolve the ambiguous bucket — it declines to bill for it. If it cannot reach a definitive result, it refunds the credit.

That candour runs deeper than billing and deserves genuine credit. Kickbox also refuses to sell spam-trap detection, stating plainly that traps cannot be identified systematically and that it therefore does not identify them, while most of the category sells the feature anyway. And its 95% accuracy guarantee is the most modest headline number here, in a market where nearly everyone claims 99% or better. A vendor that refuses to sell a capability it distrusts is telling you something real about how it will label your catch-all results.

Verdicts return in real time as deliverable, undeliverable, risky or unknown, plus a proprietary Sendex score. Catch-all lands in risky or unknown and stops there — no gateway fingerprinting, no provider-API path. Prepaid packs only: $5 for 500, $500 for 100,000, $2,999 for 1,000,000.

Best for: cold-email senders, small marketing teams and agencies that would rather not pay for verdicts they cannot act on.

vs EmailShield: EmailShield resolves the ambiguity instead of parking it, at $49 per 100,000 against Kickbox's $500. Kickbox wins one thing cleanly — it hands the credit back when it cannot answer. On a mostly Google Workspace list, where catch-all runs near 0.2%, that refund is worth more than resolution.

4. Scrubby

Scrubby is a catch-all specialist that says openly it is built to sit alongside a primary verifier rather than replace one. Its method is the genuinely different one here: instead of probing at the protocol level, it sends real blank messages at scale to the risky slice and observes whether they bounce, producing a hard valid/invalid answer rather than a probability, at a published 98% accuracy on hard-bounce detection. Two trades come with that: turnaround is reported at 24 to 72 hours rather than real time, and live messages reach real prospect mailboxes.

Pricing. STARTER $47/mo for 6,000 credits, PRO $497/mo for 100,000. The detail that decides cost modelling: quick verify consumes 1 credit, deep verify 3 — so a PRO plan buys roughly 33,000 deep verifications at about $0.0149 each.

Best for: agencies, outbound and SDR teams with a residual catch-all bucket on high-value accounts, already through a primary verifier.

vs EmailShield: EmailShield for the full-list pass — real time, roughly ten times cheaper, classifying catch-all at domain level before probing. Scrubby wins on its narrow ground: stubborn domains where an observed bounce justifies a three-day wait and three credits each.

5. BounceBan

BounceBan attacks the same bucket from the opposite direction: it resolves catch-all addresses without sending anything, claiming over 97% accuracy on more than 90% of them, and positions that against methods pushing live test traffic into a prospect's mailbox. A legitimate differentiator, particularly in Europe, and it answers in real time where send-and-observe takes days.

The verdict is catch-all-specific rather than a full taxonomy — it tells you whether it verified the address, not much more. Credits roll over, single checks in Free Mode are free, and pricing runs off a credit slider with no fixed per-credit figure published. "Proprietary algorithms" describes ownership rather than mechanism.

Best for: cold-email senders and agencies in privacy-sensitive markets wanting a catch-all-only layer on an existing stack.

vs EmailShield: both refuse to send mail and both answer in real time. EmailShield publishes the machinery — probe counts, eight named gateways, the M365 path resolving 23.5% of verdicts — and verifies the whole list. BounceBan wins if you want a bolt-on.

6. Bouncer

Bouncer's distinguishing feature is commercial rather than technical. Credits never expire, minimum purchase is 1,000, and it charges for neither duplicates within a list nor unknown results. Packs run $8 for 1,000, $400 for 100,000 and $2,000 for 1,000,000, and a Deliverability Kit adds inbox placement and SPF/DKIM/DMARC checks from $25/mo.

On catch-all it is conventional: the label returns inside a deliverable/undeliverable/risky/unknown set, in real time, with no resolution attempt. Bouncer's own pages state no accuracy percentage in quotable text; a 99.5% figure circulating on review sites is not treated as a vendor claim here.

Best for: email marketers, agencies and RevOps teams that buy in bursts and want never-expiring credits with no billing for unknowns.

vs EmailShield: EmailShield is ten times cheaper at 100,000 ($49 against $400) and resolves catch-all where Bouncer returns it. Bouncer wins on billing terms.

7. Clearout

Clearout bundles verification with an email finder and enrichment and markets an "Advanced Catch-All Resolver" plus an AI Verdict score. The resolver is described by outcome rather than mechanism — no probe count, no gateway list, no provider-API path — so what a buyer can verify is the output: a verdict plus a score, real time, credit billed regardless.

Entry is $21 for 3,000 emails, rising through $350 for 100,000 to $1,100 for 1,000,000, and credits never expire. Its published connector list — Apollo.io, HubSpot, GoHighLevel and a Google Sheets add-on — is genuinely broader than EmailShield's, which is API-first.

Best for: email marketers, agencies and RevOps teams wanting list building, verification and pre-built CRM connectors in one place.

vs EmailShield: EmailShield wins on published method and price, $49 per 100,000 against $350. Clearout wins on scope: an email finder plus a published connector catalogue.

8. Allegrow

Allegrow sits adjacent to this category, working on lead quality and sender reputation rather than selling list cleaning by the credit. Catch-all appears there as a workflow signal, not a row-level verdict on an uploaded file, and there is no self-serve pricing.

Its relevance is the February 2026 test: a stated sample of 1,222 addresses, a stated split of 989 fabricated and 233 real permutations, and a stated method. Allegrow is a commercial competitor of ZeroBounce and published it on a page selling against ZeroBounce — an interested party's benchmark, but publishing a sample and a method at all is more than most of this category manages.

Best for: SDR teams and outbound leaders treating catch-all as a lead-quality and sender-reputation problem, not a list-cleaning line item.

vs EmailShield: EmailShield for verification — first-party catch-all data at platform scale, resolution paths named. Allegrow wins on having published a controlled catch-all test, as an interested party.

9. LeadMagic

LeadMagic is primarily an email finder and enrichment API with verification on the same credit pool. Its catch-all behaviour shows up in billing more than in verdicts: credits are charged only on valid results, so an unresolvable catch-all costs nothing and returns nothing actionable. Granularity is thin — valid or not — with no catch-all label or resolution path published. Basic is $49.99/mo, higher plans from $99/mo, per-credit as low as $0.007 annually.

Best for: outbound teams and RevOps engineers who find and enrich contacts in one API and want verification on the same credits.

vs EmailShield: different jobs, and running both is reasonable. EmailShield resolves catch-all and publishes how; LeadMagic finds and enriches and charges only on valid results.

The 12-stage verification pipeline, published in full

No other vendor here publishes its verification sequence. EmailShield's, in order:

Stage 6 runs before stage 8, which is why a catch-all domain is identified as a domain rather than inferred one address at a time. Stages 7 and 9 are the recovery paths.

Straight verdict numbers on what remains

Some catch-all domains are genuinely unprovable at the SMTP level: a domain that accepts every recipient and has no secondary resolution path cannot yield proof of mailbox existence to anyone.

What separates tools is how far they shrink that bucket and whether they report the residue truthfully. What fails both recovery paths stays labeled catch-all with a confidence score, and EmailShield publishes the residue: 8.4% catch-all and 15.6% unknown or protected across 8.19M verified addresses. Reporting those figures rather than folding them into valid is why the EmailShield valid rate reads 53.3% instead of something more flattering — the difference between a verdict you can plan around and a number designed to look good.

The alternative shows up in the bounce log. A client brought a list a legacy verifier had marked 100% valid; the campaign bounced 7%, well over Google's 2% threshold, because much of it sat on catch-all domains where acceptance had been counted as proof of existence.

Choose something other than EmailShield if...

• Choose NeverBounce if you need a contractual bounce-rate guarantee in writing.
• Choose a tool with a published connector catalogue — Clearout, for example — if you cannot build against a REST API.
• Choose Reoon if per-credit price at low monthly volume is the deciding factor.

How to choose

By recipient mail infrastructure. This matters more than list size and almost nobody segments on it. Google Workspace ICP: catch-all is near a non-problem at 0.2%, so price decides. Microsoft 365 ICP — 35.9% of B2B mailboxes — only 51.4% verify valid over the protocol alone, so a secondary path is worth real money. Enterprise ICP behind Proofpoint, Mimecast or Barracuda: 30.1% of those addresses resolve catch-all, and a tool reporting them flat valid is guessing on a third of your list.

By list provenance. Purchased and scraped lists carry the highest catch-all share, plus about 5% of addresses on domains with no working mail records. Opt-in lists still rot at 2-3% a month.

By volume. At 100,000 verifications EmailShield costs $49 and leaves 76,000 usable addresses, or $0.00065 each. Kickbox at $500 and Bouncer at $400 improve once their no-charge-for-unknowns policies apply, to $0.00546 and $0.00437. Below 10,000 a month, free tiers decide it and EmailShield's 40,000 go furthest.

Where EmailShield Fits

Hold any verifier to one standard: make it tell you what happens to an address whose own mail server refuses to answer honestly about it. Ask for the count of catch-all domains it has classified, the denominator, the probes it sends, and what it names the result. A vendor who can answer has a method; one who answers with a percentage has a marketing claim.

EmailShield's answer is on the record: 160,845 catch-all domains fingerprinted out of 2.09M profiled, eight named perimeter gateways, up to five probes per domain, 23.5% of all verdicts resolved through the Microsoft account path, and 8.4% catch-all plus 15.6% unknown reported straight — at 99.8% accuracy and $49 per 100,000 credits. Verification runs on EmailShield-owned infrastructure, so uploaded lists never leave the network, encrypted in transit and at rest.

If catch-all is the bucket eating your list, run a sample. The 40,000 free credits cover a working segment, and the verification module exports each verdict category separately.

FAQ

What does catch-all mean in email verification? A catch-all domain accepts mail for every possible recipient, so the server says yes whether or not the mailbox exists. Across 2.09M domains profiled by EmailShield, 160,845 (7.7%) behave this way and 8.4% of a typical B2B list sits on one. EmailShield resolves a large share through gateway fingerprinting and a Microsoft 365 account-discovery path.

Which email verification tool is most accurate on catch-all domains? EmailShield, at 99.8% accuracy — a vendor statement measured in production across 8.19M verified addresses — and $49 per 100,000 credits. It is the only tool here publishing a catch-all method with numbers attached: 160,845 domains fingerprinted out of 2.09M profiled, up to five probes per domain, and eight named gateways.

Should I email catch-all addresses or remove them? Segment them rather than deleting them. Dropping every catch-all address removes real mailboxes at enterprises fronted by Proofpoint, Mimecast or Barracuda. Send on a separate schedule and watch bounce rate against Google's 2% threshold.

Methodology

Competitor figures. Every competitor figure was captured from a property the vendor controls on 24-25 July 2026; the signature lines under the tables list the sources. ZeroBounce and BounceBan price through a credit slider, so no per-credit figure is quoted. Clearout's figures come from its own comparison page and are directional. Scrubby's 24-72 hour turnaround is reported in third-party reviews. Any statement that a vendor publishes no methodology describes their published material as of July 2026.

Cost per usable address. The derived column divides each vendor's list price at the 100,000-verification tier by the addresses left after removing what you were billed for but cannot act on, applying one shared composition to every vendor — 15.6% unknown or protected plus 8.4% catch-all, Q3 2026 EmailShield platform data. Where a vendor's page states unknowns are not billed (Kickbox, Bouncer, ZeroBounce) only the catch-all share applies. It normalizes pricing; it does not measure accuracy.

EmailShield figures. First-party production measurements from Q3 2026 platform data: 8.19M+ addresses verified, 2.09M+ domains profiled, 37.1M+ live SMTP handshakes at an average 4.5 probes per verdict, 160,845 catch-all domains fingerprinted, 23.5% of verdicts resolved through the Microsoft 365 account-discovery path, 30.1% catch-all on gateway-fronted addresses. The 99.8% accuracy figure is a vendor statement, measured in production across those 8.19M addresses. Verification runs on EmailShield-owned infrastructure with zero third-party verification calls.

The Allegrow benchmark. The 8.1% false-positive figure for ZeroBounce comes from a test published by Allegrow in February 2026 across 1,222 addresses, 989 fabricated and 233 real permutations. Allegrow is a commercial competitor of ZeroBounce and published it on a page selling its own product — a competitor-published benchmark, not independent evidence.

One limitation on the EmailShield side: it bills the credit for an unknown verdict, where Kickbox and Bouncer do not.

Last updated: July 2026. Related reading: how catch-all domains behave, how email verifiers work, the ZeroBounce alternative comparison, and pricing.

Platform statistics used: 160,845 catch-all domains out of 2.09M profiled (7.7%); the 30.1% gateway catch-all rate; the 8.4% catch-all and 15.6% unknown/protected composition; 37.1M+ handshakes at 4.5 probes per verdict; the 23.5% M365 API resolution share. Citable asset: Verification Pipeline.

Levi Nagy is Head of Operations & Client Success at EmailShield, working with outbound and lifecycle teams on list hygiene, catch-all segmentation and deliverability operations.