A sales lead is a person or company that has shown a reason to believe they could buy: a form fill, a trial, a profile match, a referral. Leads are graded by how strong that reason is, from marketing qualified to sales qualified to product qualified. A verified sales lead adds reachability: the email was confirmed deliverable. In the lists we verified this year, 14.5% of business lead addresses were not. This guide covers the types, the sources, how qualification works in practice, and the workflow that keeps a pipeline honest.
| Type | Signal | Typical volume | Typical close rate | Main risk |
|---|---|---|---|---|
| Cold lead | Matches the profile; no signal from them | Thousands | Well under 1% per email | Bounces and spam complaints on an unverified list |
| MQL | Engaged with content or a campaign past a score | Hundreds | 1 to 5% | Scoring rewards curiosity, not need |
| SQL | A salesperson confirmed need, authority, budget or timing | Tens | 15 to 30% | Qualification done on a call, not from data |
| PQL | Used a free tier or trial in a way that predicts purchase | Tens | 20 to 40% | Only exists if the product has a free entry point |
| Referral | Introduced by a customer or partner | Few | 30% and up | Hard to scale |
Close rates are ranges seen across B2B SaaS and services teams; measure your own by type before setting targets.
Source sets quality before anyone qualifies anything. The invalid rates are from the 2026 lead list quality benchmarks, 7.93 million addresses verified by BounceZero between April and October.
Typed by the owner, with intent. Still 5 to 10% invalid from typos and throwaways; validate at the form with the API so sales never calls a dead address.
The strongest signal and the cleanest data, because the address logged in. Score usage events, not page views.
Small numbers, highest close rate. The only source where verification is a courtesy rather than a necessity.
Real people, often personal or temporary addresses. Re-verify thirty days later; attendees' work addresses change.
Apollo, ZoomInfo, Lusha, Cognism, Hunter. Broad and fast; 10 to 25% of exports bounce without verification. See email finders.
Benchmark: about one invalid address in seven if not verified in 90 days; .au lists 36.5% invalid. Buy only with a verified random sample.
Highest share of role addresses and catch-all domains; lowest reachability. Verify, segment by provider, and expect to discard a third.
BANT asks four things: budget, authority, need, timing. MEDDIC asks six: metrics, economic buyer, decision criteria, decision process, identified pain, champion. Both assume you can reach the person. Neither has a line for "does the email work", which is why reachability belongs in the lead score before the frameworks are applied.
Industry, size, geography, stack. Firmographic and technographic data from enrichment. Weight: 40%.
Form fills, trial actions, content depth, replies, hiring and funding triggers. Weight: 40%.
Email verified valid in the last 90 days; phone confirmed; LinkedIn active. Applied as a multiplier on the fit and intent total: 1.0 for a confirmed address, 0.5 for catch-all or unknown, 0 for invalid. The same factors are used on the SaaS scoring guide and in the glossary.
The weights are a starting point. Lead scoring with real conversion data is covered in the sales prospecting guide and the B2B prospecting process.
Non-freemail (business and ISP) domains return unknown 27% of the time because ISP and corporate gateways and ISPs block verification probes. A vendor that reports no unknowns is guessing on a quarter of your list.
| Segment | Addresses | Invalid | Catch-all | Unknown | Confirmed valid |
|---|---|---|---|---|---|
| Non-freemail (business and ISP) domains | 6,514,884 | 14.5% | 2.3% | 27.0% | 32.6% |
| Freemail on B2B lists | 1,415,154 | 17.6% | 1.1% | 2.1% | 74.0% |
| gmail.com | 801,225 | 3.5% | 0.0% | 0.0% | 96.0% |
| hotmail.com.au | 110,452 | 92.7% | 0.0% | 3.1% | 2.3% |
Full tables by country domain and provider: Lead List Quality Benchmarks 2026.
Forms and CRM imports go through real-time or bulk verification before a lead record exists. Invalid never enters the pipeline; catch-all and unknown enter flagged.
Apply fit and intent, then multiply by reachability. A great-fit lead with a catch-all address ranks below a good-fit lead with a confirmed mailbox.
Confirmed addresses to cold and nurture sequences. Flagged addresses to phone, LinkedIn or a warm low-volume sequence on a secondary domain. Guide: cold email verification.
Leads in the CRM decay fast, with only 19.2% of addresses still valid 90 days after verification in the BounceZero decay study. A re-check before every send of open leads keeps sequences under the 2% bounce threshold and surfaces job changes as new intent signals.
Sources ranked by quality, build vs buy
Eight methods ranked by return
Six steps and the tools for each
Tools by stage, with data accuracy notes
How finders work and which to use
The data behind this page
A lead has shown a reason to believe they could buy or has matched your profile; a prospect is a lead a salesperson has qualified and chosen to pursue. Prospecting is the work of turning leads into prospects. The sales prospecting guide covers that process; this page covers what you feed into it.
MQL, marketing qualified, means the person engaged with content or campaigns enough to pass a score threshold. SQL, sales qualified, means a salesperson confirmed need, authority, budget or timing. PQL, product qualified, means they used a free tier or trial in a way that predicts purchase. PQLs convert best; MQLs are the cheapest and the noisiest.
It depends on where the leads come from. Inbound demo requests can close one in five. Cold-sourced leads from databases close one in several hundred emails sent, before bounces. The bounce rate is the hidden multiplier: at 15% invalid, about one in seven of the emails you pay to send never reaches a mailbox, and a bounce rate above the 2% industry limit damages the sending domain.
Fit, intent and reachability. Fit is the ICP match. Intent is the signal they gave. Reachability is whether the contact channel works; an unverified email is an unreachable lead with a confident label. A list that is 95% fit and 70% reachable performs worse than one that is 80% fit and 98% reachable: 95 x 0.70 = 66.5 against 80 x 0.98 = 78.4.
Run new leads through a verifier that reports valid, invalid, catch-all and unknown separately, at import and again before every send. Route only confirmed addresses to cold sequences. BounceZero does this in bulk, through the API on your CRM or form, and gives every account 100 free checks a month.
Verify at the form, in bulk, or from your CRM. 100 free checks a month, bulk jobs to a million rows, 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.
Where leads come from, how finders work, and what a verified lead is - with 2026 corpus data
Where verification sits in the funnel
Seven sources ranked by data quality, build vs buy, the verify-enrich-score-segment workflow
How finders work, Hunter vs Apollo vs Snov vs Clay, finder vs verifier
Extensions, Sales Navigator exports, accuracy, the legal line
7.93M addresses: invalid, catch-all and unknown rates by provider and country
Verify an email list in bulk
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