.co is the country domain used in startups and Colombia. Across 6,159 .co addresses verified by BounceZero between April and October 2026, 17.1% were invalid, 25.6% catch-all, 15.3% unknown and 38.7% confirmed valid. Catch-all and unknown together mean a large share cannot be confirmed.
The .co row is all 6,159 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 |
|---|---|---|---|---|---|
| .co | 6,159 | 17.1% | 25.6% | 15.3% | 38.7% |
| 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 .co row: 3.4%.
Used by startups worldwide and by Colombian businesses; small domains churn, so invalid rates run above .com.
The .co domain is used by startups worldwide as a .com alternative and by Colombian companies. Startup domains change hands, rebrand and shut down more often than established companies, which drives the invalid rate above .com, and small hosting plans produce a high catch-all share. Quarterly re-verification is the minimum for a startup-heavy list, and finder guesses on .co domains should be tested before use. Colombian companies on .com.co verify at rates closer to the business average than the startup share does, so a .co list should be split by whether the domain is a Colombian company or a global startup before its quality is judged. Startup mail is almost always on Google Workspace, whose gateway answers probes clearly, which means the invalid results on startup domains are reliable and usually permanent.
On confirmed-invalid rate, .co ranks 9 of 23 country domains in the corpus, just behind .net at 17.6%, ahead of .uk at 17.0%.
On unknown rate, .co ranks 13 of 23 country domains in the corpus, just behind .au at 17.6%, ahead of .ae at 14.9%.
On confirmed-valid share, .co ranks 14 of 23 country domains in the corpus, just behind .be at 40.5%, ahead of .edu at 38.1%.
How to read these rates: they are BounceZero's probe outcomes on customer lists over April to October 2026, not a census of .co 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.
15.3% of .co probes come back unconfirmed. Treat them as a separate segment: no cold volume, a re-check in seven days, and a second channel if they stay unknown.
17.1% of .co addresses are confirmed invalid, close to the 14.5% seen across non-freemail lists. Delete them; there is nothing to re-check.
Catch-all is the defining trait here: 25.6% of .co addresses accept anything, so finder guesses look valid and bounce later. Hold them out of cold sequences entirely.
38.7% of .co addresses confirmed as deliverable at verification time and can go straight to the primary sequence, with a re-check before every send.
Verify quarterly; startup domains change hands and shut down more often than established companies.
Role addresses such as info@ and sales@ make up 18.6% of .co addresses in the corpus. Role addresses rarely reach a person; prefer named contacts.
17.1% of 6,159 .co addresses verified by BounceZero between April and October 2026 were confirmed invalid, against 14.5% across non-freemail domains and 17.6% across freemail.
15.3%. 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.
Partly: 25.6% of .co addresses sat behind a catch-all accept, so the server took any address and the mailbox could not be confirmed.
38.7% 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 .co 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
7,561 .ca addresses verified April to October 2026
30,522 .ch addresses verified April to October 2026
2,158,955 .com addresses verified April to October 2026
2,095,440 .de addresses verified April to October 2026
65,636 EarthLink addresses verified April to October 2026
17,961 .edu addresses verified April to October 2026
Continue through related topics