A lead list is a set of contacts assembled for a particular campaign or segment, usually as a spreadsheet or CRM import: name, company, title, email, sometimes phone. It is a snapshot, which is what separates it from a lead database that is maintained over time. Lists bounce at rates set by their source: inbound forms at 5 to 10% invalid, finder exports at 10 to 25%, and bought lists at about one address in seven if not verified within 90 days.
List quality is measured by verifying it: invalid, catch-all, unknown and valid shares, plus the share of role addresses and freemail domains, which predict reply behaviour. A clean B2B list runs under 3% invalid, under 5% role addresses, and carries a verified-at date.
The business leads list page describes the five-minute test for a list someone is selling; the list generator guide covers building one from scratch.
Three lists of 2,000 for the same campaign: an inbound export verifies at 93% valid, a finder export at 78%, a bought file at 61% with 9% role addresses. Priced on confirmed-valid rows, the bought file cost twice as much per reachable contact as the finder export, despite a lower sticker price.
Verify a list or a single address. 100 free checks a month, unknowns refunded.
Verify Leads - FreeAyoub 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.