Buyer's guide

How to verify B2B data before you buy it

Before you trust a B2B data vendor with your budget, test a sample. Export 200 to 500 contacts, measure how many bounce, how many you already have, and how many have moved on, and you will know what the full list is worth before you pay for it.

Why you test the sample, not the sales pitch

Every vendor says its data is verified. The word does a lot of quiet work. It can mean the address was checked the day it was added, which might be years ago, rather than today. Because people change jobs continuously, even a genuinely clean list goes stale on a schedule, so a label on the tin is not the same as a working contact.

The only reliable answer is to measure. A small sample, checked properly, tells you more than any data sheet, and it costs you almost nothing to run.

The 200 to 500 contact sample test

Step 1: Take a representative sample

Ask for, or pull, 200 to 500 contacts from the same segments and filters you would buy for real. A sample cherry-picked by the vendor is not a fair test, so choose it the way you would choose the full list.

Step 2: Measure the bounce rate

Check every email at the mail server and count the invalid ones. Under 1 percent is healthy, and anything climbing toward 2 percent tells you the list will hurt your sender reputation before it wins you a meeting.

Step 3: Check for overlap with what you own

Match the sample against your own CRM. Contacts you already have are contacts you would be paying for twice, and a high overlap rate quietly changes the real price per new contact.

Step 4: Count how many have moved on

See how many contacts look to have changed role or organisation since the data was captured. Those are the records that will send your reps to a person who no longer works there.

Reading the result

A vendor worth buying from returns a sample that bounces under 1 percent, overlaps little with what you already own, and shows few contacts who have obviously moved on. If the sample fails on any of those, the full list will fail harder, because the problems scale with the volume.

Run the same test on every vendor you are weighing up, and you are comparing measured results rather than marketing claims. Verify before you trust, not after the invoice.

Verifying B2B data, common questions

How do I verify a B2B data vendor before buying?
Test a sample before you commit to the full list. Ask for or export 200 to 500 contacts, then measure how many bounce when checked at the mail server, how many are duplicates of records you already hold, and how many have changed role or organisation. A vendor whose sample is clean on all three is worth trusting with a larger purchase. One that is not tells you before you have spent the budget.
How big a sample do I need to test a data provider?
Between 200 and 500 contacts is enough to see the pattern. It is large enough that the bounce and duplicate rates are meaningful, and small enough to check quickly. Pick the sample the way you would buy the real list, from the same segments and filters, so the test reflects what you would actually receive.
What does verified data from a vendor actually mean?
It varies, which is the problem. Verified can mean the address was checked when it was first added, months or years ago, rather than today. Data decays continuously as people change jobs, so a label alone is not proof. The reliable test is to check the sample yourself at the mail server and against your own records, rather than trusting the word verified on the tin.
Can I check a data sample for free?
Yes. Datuma scores up to 100 contacts free, with no card. Upload a sample from any vendor and you get back a bounce check at the mail server, a duplicate check against your own lists, a flag for anyone who looks to have moved on, and a Trust Score from 0 to 100 per contact, so you can see exactly what a list is worth before you buy more of it.

Score a sample from any vendor, free

Upload up to 100 contacts from any list and Datuma checks the emails at the mail server, catches the duplicates against your own records, flags the people who look to have moved on, and scores every contact from 0 to 100. See what a list is worth before you buy more of it.

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100 contacts · 5 minutes