A bad list does more damage than no list: bounces wreck your sending reputation, spam complaints follow, and recovering a burned domain takes months.
We build and sell attendee lists, so we see the failure modes constantly. This is the checklist we apply internally before any dataset is delivered — use it on any vendor, including us.
Ask where the data came from
There is a real difference between a list scraped from a directory, a list generated by pattern-guessing email formats, and a list built from a defined, verifiable population such as the attendee body of a specific event.
Event-derived data has a natural qualifier baked in: everyone on it paid attention to a specific market at a specific time. That context is what makes the first line of your email possible.
The five quality checks that matter
- Deduplication method — across the whole set, not per file. Our 26-event bundle collapses 140,166 raw rows into 114,693 unique people.
- Consumer-domain ratio — a high share of gmail/hotmail addresses signals scraped or self-registered data of lower business value.
- Field completeness — what percentage actually has a company, a title and a working email, not just a name.
- Recency — B2B data decays roughly 2–3% per month through job changes alone.
- Channel mix — email only, or email plus phone. Price and use case differ significantly.
Always request a sample before paying
A credible vendor will show you a real sample with the same field structure as the full delivery. Run it through your verification tool of choice, check bounce projections, and confirm the titles match what was described. We publish sample sheets for every conference list for this reason.
Ramp sending — never blast a fresh list
Send from a secondary domain, never your primary. Authenticate with SPF, DKIM and DMARC before the first send.
| Week | Daily volume per mailbox | Focus |
|---|---|---|
| 1 | 20–30 | Warmest segment, highest personalisation |
| 2 | 40–50 | Monitor bounce and complaint rates |
| 3 | 60–80 | Expand segments if bounce rate stays under 3% |
| 4+ | Steady state | Rotate mailboxes, keep per-mailbox volume modest |
Compliance is not optional
- GDPR: for EU contacts, rely on legitimate interest for B2B outreach, document the assessment, and honour objections immediately.
- CAN-SPAM: accurate headers, physical address, working unsubscribe in every message.
- Keep a permanent suppression list and apply it across every sending tool you use.
What we publish for each list
Every conference list on Mapdad shows the record count, channel mix (email only, or email plus phone), location, event date and a description of who is actually in it — plus a sample sheet before purchase. Where a dataset has caveats, we state them on the page rather than in the footnotes.
Frequently asked questions
Is buying B2B lead lists legal?
In most jurisdictions, yes for business-to-business outreach, provided you comply with local rules — GDPR legitimate interest in the EU/UK, CAN-SPAM in the US — and honour opt-outs promptly.
What bounce rate should I expect?
On a verified B2B list, budget for a low single-digit percentage. Anything approaching 5% should pause the campaign while you re-verify.
How fast does lead data decay?
Roughly 2–3% per month from job changes alone, which is why recent event data outperforms older directory data.
Can I see a sample before buying?
Yes. Every conference list has a sample sheet, and the full sheet is delivered after payment is confirmed.
Verified attendee data, 29 events
114,000+ deduplicated people. Buy a single list, or the all-in-one bundle at 78% off.
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