A B2B email marketing list is a purchased or licensed file of business contacts, each with a work email, name, title and company, sold for outbound campaigns. In the BounceZero corpus of 6.5 million non-freemail (business and ISP) addresses verified between April and October 2026, 14.5% were invalid and 27% could not be confirmed, which is why a list is only worth what survives verification, not what the vendor counts.
Sometimes, with conditions. A bought list is the fastest way to reach a defined segment you have no inbound path to, such as plant managers in a region, or finance leads at firms of a certain size. It is also the fastest way to burn a sending domain, because the vendor counts rows and your mail server counts bounces.
BounceZero does not sell lists. We verify them, which puts us on the receiving end of what list buyers actually get. This page is written from that vantage point: the bounce rates we measure by source, the checks that separate a usable file from a liability, and a free way to test before you pay.
The rule that matters most: sending platforms suspend accounts whose bounce rate passes roughly 2%, and Google and Microsoft act on complaint rates above 0.3%, and a typical unverified bought list bounces at seven times that. Every other section here exists to get you under 2%.
These are verification outcomes on business-domain addresses from the BounceZero corpus, April to October 2026, cut by the domain ending most common in purchased files. "Unknown" means the receiving server would not confirm or deny the mailbox; a vendor that reports none is guessing on a quarter of the file.
| Domain ending | Addresses verified | Invalid | Catch-all | Unknown | Confirmed valid |
|---|---|---|---|---|---|
| .com | 2,158,955 | 16.4% | 4.4% | 14.7% | 59.7% |
| .co.uk and .uk | 21,194 | 17.0% | 3.7% | 10.6% | 65.0% |
| .de | 2,095,440 | 13.9% | 0.0% | 41.2% | 16.5% |
| .au | 560,378 | 36.5% | 6.3% | 17.6% | 37.3% |
| .org | 56,401 | 24.6% | 12.4% | 25.0% | 36.2% |
| .us | 10,998 | 34.1% | 13.6% | 21.9% | 29.1% |
| All non-freemail (business and ISP) domains | 6,514,884 | 14.5% | 2.3% | 27.0% | 32.6% |
Source: Lead List Quality Benchmarks 2026. .de unknowns are dominated by t-online.de, which refuses verification probes; treat German lists as needing a warm-up send rather than a verdict.
Four mechanics explain the gap. None of them require the vendor to be dishonest.
Most vendors verify at ingest. Business addresses decay fast, with only 19.2% of addresses still valid 90 days after verification in the BounceZero decay study as people change jobs, so a file verified nine months ago has lost about a sixth of its mailboxes before you open it.
A catch-all domain accepts mail for any local part during verification and bounces it later or drops it silently. In the corpus 2.3% of non-freemail (business and ISP) addresses sit on catch-all domains overall, 12.4% on .org. Vendors count these as good.
When a vendor has the company pattern but not the person, the row is generated as first.last@domain and scored on the pattern's past hit rate. These guesses are indistinguishable from observed addresses in the export.
info@, sales@ and office@ rows pad counts, rarely reach a buyer, and attract complaints. A clean B2B file carries under 3% role addresses; bought files often run 10 to 20%.
Prices are vendor-reported ranges as of 2026 and move with volume. The accuracy column is what buyers typically see after an independent verification of the export, not the vendor's claim.
| Vendor type | Examples | Typical price per contact | Invalid after verification | Best for |
|---|---|---|---|---|
| Subscription database | ZoomInfo, Apollo, Cognism, Lusha | $0.10 to $1.00 (vendor-reported) | 10 to 22% | Ongoing prospecting with filters, not one-off files |
| List broker | Regional and industry brokers | $0.15 to $0.60 (vendor-reported) | 12 to 30% | Niche verticals a database does not cover |
| Marketplace file | Downloadable CSV sellers | $0.01 to $0.10 (vendor-reported) | 25 to 45% | Rarely; usually recycled data |
| Compiled from directories | Trade bodies, registries | Often free to low | 15 to 35% | Local and regulated industries |
| Your own build | Finder plus verifier | $0.05 to $0.20 all-in | 5 to 10% before verification, under 2% after | Any segment you can describe |
Subscription vendors compared in depth: B2B email list providers 2026. Export accuracy by vendor: ZoomInfo, Apollo, Cognism.
Ask for these in writing. A vendor who cannot answer six of them is selling you a spreadsheet, not data.
Not "we verify continuously". A column with a date. Anything older than 90 days is a re-verify job, priced accordingly.
Observed (seen in a signature, a form, a partner feed) or inferred (pattern). Inferred rows bounce two to three times more often.
A separate column, or at least a count. If the vendor cannot tell you, assume 5 to 12% of the file is unconfirmable.
Count of info@, sales@, admin@ and similar. Ask for them to be excluded or discounted.
gmail.com and outlook.com rows in a "business" file are usually sole traders or stale. Fine for some segments, padding in others.
Same person at two companies, or same address twice. Ask for a unique count, not a row count.
Most reputable vendors replace hard bounces reported within 30 days. Get the threshold in the contract.
Under UK GDPR and PECR, B2B marketing to corporate addresses can rest on legitimate interest, but the vendor must show where consent or interest was established, and you must honour opt-outs within days.
Existing customers, unsubscribes and competitors should be removed before pricing, not after.
A random 200 to 500 rows, not the vendor's top rows. Verify it yourself before signing.
Single use, multi-use, or perpetual. Single-use files are cheaper and often enough for one campaign.
CSV with a stable ID per row so bounces can be reported back for replacement.
Ask the vendor for a random sample of 200 rows. Create a BounceZero account, which gives you 100 verifications a month at no cost, and run the sample in two halves or buy the Starter pack of 2,000 credits for $6. If the sample comes back over 10% invalid, or over 8% catch-all plus unknown on non-German domains, the full file will too. Walk away or negotiate a replacement clause before paying. Unknowns are refunded, so you only pay for answers.
Thresholds that separate a usable B2B file from one that will damage the sending domain. They are stricter than the corpus averages on purpose; the averages include everything people upload, including lists they already suspected.
| Result | Good file | Marginal | Walk away |
|---|---|---|---|
| Invalid | Under 5% | 5 to 10% | Over 10% |
| Catch-all | Under 4% | 4 to 8% | Over 8% |
| Unknown (outside .de) | Under 6% | 6 to 12% | Over 12% |
| Role addresses | Under 3% | 3 to 8% | Over 8% |
| Freemail in a "business" file | Under 5% | 5 to 15% | Over 15% |
| Disposable or spam-trap flags | 0 | 1 or 2 rows per 500 | Any more |
Spam traps are the one category where a single hit matters more than the rate; one trap on a blocklist can cost you weeks. Check with the spam trap checker before any send.
Bulk verification handles up to a million rows per job. Keep the vendor's row ID in a column so hard bounces can be claimed back under the replacement clause.
Valid to the main sequence on the primary domain. Catch-all to a low-volume warm sequence on a secondary domain. Unknown to a re-check in a week. Invalid to the refund claim.
Start at a few hundred a day per domain and double weekly while bounces stay under 2% and complaints under 0.3%. A bought list that passes verification still has no engagement history with your domain.
A quarter of the way through the decay curve. The list decay study measured how fast mailboxes disappear; re-checks before every send are the cheapest insurance against it.
In the UK, PECR treats corporate subscribers differently from individuals: you may email a named person at a company address without prior consent, provided the message is about your business, identifies you, and offers a working opt-out. UK GDPR still applies to the person's data, so you need a documented legitimate interest and a privacy notice that says where you obtained the address. Sole traders and partnerships count as individuals and need consent.
In the EU the picture varies by member state; Germany and Austria are strict, the Netherlands and Ireland closer to the UK. In the United States CAN-SPAM permits unsolicited B2B email with identification, a physical address and an opt-out honoured within ten days. Canada's CASL requires consent or an existing relationship. None of this is legal advice; it is why the "lawful basis" question is on the checklist above. The GDPR compliance guide goes deeper.
The full corpus tables by provider and country
Subscription databases on coverage, accuracy and price
Marketplaces and vendor types, with the pre-purchase checklist
The finder plus verifier route, step by step
What to do with a file you already bought
Sources ranked by data quality
In the UK and most of the EU, yes for corporate addresses, provided you have a documented legitimate interest, identify yourself, say where you got the address, and honour opt-outs. Sole traders count as individuals and need consent. In the US, CAN-SPAM allows it with identification and an opt-out. The vendor must be able to show the lawful basis for collection; if they cannot, do not buy.
Vendor-reported ranges in 2026 run from a cent per contact for marketplace CSV files to a dollar or more for enriched subscription data with phone numbers and intent signals. Price tracks freshness more than anything else. A cheap file is usually a recycled one, and recycled files bounce at 25 to 45%.
Unverified, 10 to 30% depending on the vendor type, against a 2% threshold at Gmail and Microsoft. Verified first and sent only to confirmed addresses, under 2%. The difference is the verification step, which costs a fraction of a cent per row.
Yes. Ask for a random sample of 200 to 500 rows and verify it yourself. BounceZero gives every account 100 free checks a month and a 2,000-credit pack costs $6. If the sample fails the thresholds on this page, the full file will too.
For a segment you can describe by title, company size and geography, building with a finder and verifying costs about the same per contact, gives you fresher data, and leaves you with a repeatable process. Buying wins when the segment is obscure or you need it this week. Many teams do both: buy for speed, build for the segments that matter most.
Upload the sample, get valid, invalid, catch-all and unknown per row, and decide with data. 100 free checks a month, unknowns refunded.
Ayoub built BounceZero's 5-stage validation pipeline, its dedicated BGP-announced IP infrastructure, and the Patroni HA PostgreSQL cluster behind every verification. Previously built high-volume email delivery infrastructure. Trained at 1337 Benguerir (École 42 network, 2019). Open-source: bgp_analyzer.
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