Luukku is a Finnish freemail (Elisa). Across 104,996 Luukku addresses verified by BounceZero between April and October 2026, 18.2% were invalid, 0.0% catch-all, 49.8% unknown and 13.1% confirmed valid. Unknown dominates because the gateway defers probes.
The Luukku row is all 104,996 addresses verified in the six months to October 2026; the other rows are the benchmarks from the same corpus. Risky and role results fill each row to 100%.
| Segment | Addresses | Invalid | Catch-all | Unknown | Confirmed valid |
|---|---|---|---|---|---|
| Luukku | 104,996 | 18.2% | 0.0% | 49.8% | 13.1% |
| All non-freemail domains (business and ISP) | 6,514,884 | 14.5% | 2.3% | 27.0% | 32.6% |
| Business domains only (consumer ISP and freemail excluded) | 1,269,919 | 22.9% | 9.4% | 22.5% | 40.3% |
| All freemail | 1,415,154 | 17.6% | 1.1% | 2.1% | 74.0% |
Non-freemail includes consumer ISP mailboxes; a business-only cut is on the benchmarks page. Method and every other cut: Lead List Quality Benchmarks 2026. Risky and role on the Luukku row: 18.9%.
Luukku is a Finnish consumer mailbox from Elisa. Half of probes return unknown because the gateway defers, and nearly a fifth are confirmed invalid. Finnish consumer lists are small, so this domain stands out when it appears.
Luukku is the free mailbox Elisa offered Finnish customers, and its addresses appear on Nordic consumer lists and on small-business records where the owner used a personal account. Finnish gateways defer probes, so half the segment cannot be confirmed by verification. Finland applies the EU rules through its own data protection act, with consent required for individuals and a legitimate-interest route for business contacts; the Luukku segment is almost entirely in the first group.
On confirmed-invalid rate, Luukku ranks 12 of 29 providers in the corpus, just behind MindSpring at 25.6%, ahead of AOL at 17.9%.
On unknown rate, Luukku ranks 5 of 29 providers in the corpus, just behind iiNet at 65.5%, ahead of Bluewin (Swisscom) at 48.4%.
On confirmed-valid share, Luukku ranks 20 of 29 providers in the corpus, just behind BellSouth at 15.5%, ahead of Xtra (Spark) at 11.2%.
How to read these rates: they are BounceZero's probe outcomes on customer lists over April to October 2026, not a census of Luukku mailboxes. Unknown and catch-all measure what verification could not confirm, which depends on the provider's gateway policy during the window as much as on the addresses. The lists are the ones customers chose to upload, so segments dominated by a few large uploads carry their age and source. Method and limitations: benchmarks page.
49.8% unknown is the story of Luukku: the gateway defers probes, and the mailboxes behind them can only be tested by a careful send.
18.2% of Luukku addresses are confirmed invalid, above the 14.5% seen across non-freemail lists. Delete them; there is nothing to re-check.
Catch-all is negligible on Luukku (0.0%); when this provider does return valid, the mailbox accepted the probe itself rather than a blanket accept.
Confirmed valid is 13.1%. Send to that slice from the primary domain and treat the rest of the Luukku segment as unreachable by cold email.
Note the risky and role share: 18.9% of Luukku results landed there, which the four headline columns do not show. Read risky as 'deliverable but with a flag' and test it at low volume before trusting it.
Route unknowns to a second channel or a later re-check. The confirmed-invalid share is high enough to treat the domain as consumer-grade and old.
Role addresses such as info@ and sales@ make up 0.0% of Luukku addresses in the corpus. Role addresses are rare here, as expected for a mailbox provider.
18.2% of 104,996 Luukku addresses verified by BounceZero between April and October 2026 were confirmed invalid, against 14.5% across non-freemail domains and 17.6% across freemail.
49.8%. Unknown means the mailbox could not be confirmed either way, usually because the gateway deferred the probe. BounceZero refunds unknown results; re-check after a week or use a second channel.
Not in practice: 0.0% of Luukku addresses returned catch-all, so a valid verdict means the mailbox exists.
13.1% confirmed valid at verification time. Keep bounces under 2% and complaints under 0.3% on the send, and re-verify the segment before every send.
Upload the file and see valid, invalid, catch-all and unknown per row, with the Luukku segment against this benchmark. 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.
Invalid, catch-all and unknown rates per email provider and country domain, 2026
22,084 Netcom (EarthLink) addresses verified April to October 2026
48,102 Live.nl (Outlook.com Netherlands) addresses verified April to October 2026
39,022 MindSpring addresses verified April to October 2026
1,252,193 .net addresses verified April to October 2026
87,309 .nl addresses verified April to October 2026
36,773 .nz addresses verified April to October 2026
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