AT&T is an US ISP mailbox (hosted by Yahoo). Across 421,292 AT&T addresses verified by BounceZero between April and October 2026, 10.1% were invalid, 0.0% catch-all, 26.4% unknown and 5.8% confirmed valid. Catch-all and unknown together mean a large share cannot be confirmed.
The AT&T row is all 421,292 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 |
|---|---|---|---|---|---|
| AT&T | 421,292 | 10.1% | 0.0% | 26.4% | 5.8% |
| 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% |
| All .net addresses | 1,252,193 | 17.6% | 0.6% | 28.8% | 19.9% |
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 AT&T row: 57.7%.
AT&T consumer addresses are hosted on the Yahoo platform, which rate-limits verification probes. A quarter of att.net addresses return unknown and a tenth are confirmed invalid. These addresses are common on older US consumer lists and on SMB lists built from public records.
AT&T issued att.net mailboxes with its consumer broadband and migrated them to Yahoo's platform years ago. The address is typical of older US consumer records, home-based businesses and local trades, and it appears on SMB lists compiled from public filings and directories. Verification probes are rate-limited by the platform, which is the source of the unknown share. CAN-SPAM permits unsolicited business email in the United States with an opt-out, but the segment is consumer-heavy and the reply rate is low.
On confirmed-invalid rate, AT&T ranks 17 of 29 providers in the corpus, just behind EarthLink at 10.7%, ahead of Yahoo Mail at 8.2%.
On unknown rate, AT&T ranks 13 of 29 providers in the corpus, just behind MindSpring at 34.8%, ahead of AOL at 19.9%.
On confirmed-valid share, AT&T ranks 24 of 29 providers in the corpus, just behind Optimum at 6.0%, ahead of PeoplePC at 2.5%.
How to read these rates: they are BounceZero's probe outcomes on customer lists over April to October 2026, not a census of AT&T 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.
26.4% of AT&T 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.
Roughly one in 10 AT&T addresses is dead, against about one in 7 across non-freemail lists.
Catch-all is negligible on AT&T (0.0%); when this provider does return valid, the mailbox accepted the probe itself rather than a blanket accept.
Only 5.8% of AT&T addresses confirmed as live mailboxes. Those few go to the primary sequence; the segment as a whole is not a cold-email segment.
Note the risky and role share: 57.7% of AT&T 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.
Treat the unknown share as unconfirmed, not dead. For US consumer-heavy lists, expect a third of att.net addresses to need either a re-check or a different channel.
Role addresses such as info@ and sales@ make up 0.0% of AT&T addresses in the corpus. Role addresses are rare here, as expected for a mailbox provider.
10.1% of 421,292 AT&T addresses verified by BounceZero between April and October 2026 were confirmed invalid, against 14.5% across non-freemail domains and 17.6% across freemail.
26.4%. 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 AT&T addresses returned catch-all, so a valid verdict means the mailbox exists.
5.8% 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 AT&T 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
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