BellSouth is a Legacy US ISP mailbox (AT&T, hosted by Yahoo). Across 134,384 BellSouth addresses verified by BounceZero between April and October 2026, 4.5% were invalid, 0.1% catch-all, 43.7% unknown and 15.5% confirmed valid. Unknown dominates because the gateway defers probes.
Every BellSouth address BounceZero verified for customers between April and October 2026, beside the corpus benchmarks. The remainder of each row to 100% is risky and role results.
| Segment | Addresses | Invalid | Catch-all | Unknown | Confirmed valid |
|---|---|---|---|---|---|
| BellSouth | 134,384 | 4.5% | 0.1% | 43.7% | 15.5% |
| 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 BellSouth row: 36.2%.
Another legacy AT&T brand on the Yahoo platform. Confirmed-invalid is low but the unknown share is above four in ten, because Yahoo throttles probes and because many of these mailboxes have been dormant for years. The confirmed-valid share is small.
BellSouth served the south-eastern United States before AT&T absorbed it, and its mailboxes were migrated to Yahoo's platform. The address appears on US lists compiled from older public records and on consumer lists from Georgia, Florida and the Carolinas. Because the platform throttles probes, the unknown share is inflated, but the age of the brand means most unconfirmed addresses are dormant. There is little to gain from re-checking.
On confirmed-invalid rate, BellSouth ranks 24 of 29 providers in the corpus, just behind SBCGlobal at 4.6%, ahead of Gmail at 3.5%.
On unknown rate, BellSouth ranks 7 of 29 providers in the corpus, just behind Bluewin (Swisscom) at 48.4%, ahead of T-Online at 41.2%.
On confirmed-valid share, BellSouth ranks 19 of 29 providers in the corpus, just behind T-Online at 16.4%, ahead of Luukku at 13.1%.
How to read these rates: they are BounceZero's probe outcomes on customer lists over April to October 2026, not a census of BellSouth 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.
43.7% unknown is the story of BellSouth: the gateway defers probes, and the mailboxes behind them can only be tested by a careful send.
Confirmed invalid is low at 4.5%, better than the business-list average of 14.5%.
Catch-all is negligible on BellSouth (0.1%); when this provider does return valid, the mailbox accepted the probe itself rather than a blanket accept.
Only 15.5% of BellSouth 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: 36.2% of BellSouth 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.
Low value segment. Verify once, keep the confirmed-valid contacts, and do not spend sequence slots on unknowns from this domain.
Role addresses such as info@ and sales@ make up 0.0% of BellSouth addresses in the corpus. Role addresses are rare here, as expected for a mailbox provider.
4.5% of 134,384 BellSouth addresses verified by BounceZero between April and October 2026 were confirmed invalid, against 14.5% across non-freemail domains and 17.6% across freemail.
43.7%. 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: 0.1% of BellSouth addresses returned catch-all, so a valid verdict means the mailbox exists.
15.5% 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 BellSouth 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
47,494 Bbox (Bouygues Telecom) addresses verified April to October 2026
28,040 .be addresses verified April to October 2026
35,207 BigPond (Telstra) addresses verified April to October 2026
21,684 Bluewin (Swisscom) addresses verified April to October 2026
8,450 .br addresses verified April to October 2026
7,561 .ca addresses verified April to October 2026
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