How Accurate Are ZoomInfo, Apollo, UpLead, RocketReach, Lusha and Cognism Emails? What Each Vendor Claims
ZoomInfo and UpLead each say their emails are 95% accurate. RocketReach publishes an estimate for each email grade. Lusha and Cognism give no email percentage, and Seamless.AI says its check is true only at the moment it runs. None of them publishes how the number is measured, on what sample, or when. Treat every figure as a claim about the vendor's database on the day of its check, then measure your own export with a 300-row sample before you send.
Every quote below comes from the vendor's own page, read on 2 November 2026, except Apollo's: its help center returned an error that day, so its row is from the article as quoted in our earlier Apollo verified emails post. We haven't measured any of these databases and this post doesn't rank them.
What each vendor says about its own emails
| Vendor | Its claim | Where |
|---|---|---|
| ZoomInfo | Contact data "verified at over 95% accuracy"; emails refreshed daily as people change roles | Email verification page |
| UpLead | "We verify email addresses with a data accuracy rate of 95%"; "a 95% data accuracy guarantee", credits back below it | Pricing, About |
| RocketReach | Grade A about 98% (personal over 99%, professional over 97%), A- about 90%, B 75 to 85%, F invalid | API FAQ |
| Apollo | A multi-step verification that includes SMTP checks plus data from its network; "verified" is a status, not a percentage | How Apollo Verifies Emails |
| Lusha | A+ "highly likely to be delivered", A "a good likelihood"; no percentage | Email confidence ratings |
| Cognism | Proprietary validation, with a research team that manually verifies customers' most requested contacts; no email percentage (its "highest accuracy" line is about phone data) | Cognism FAQ |
| Seamless.AI | Verifies when you research a contact; "the email check is only true at that moment"; no deliverability guarantee | Credit Back Protection |
What none of these numbers tell you
- What "accurate" means. Delivered without a bounce, accepted at an SMTP check, or the right person at the right company are three different measurements. None of the pages says which.
- The sample. A database-wide figure can be very different for your slice: small companies, one country, one industry, junior titles.
- The date. Every claim describes a check on a past day. Our B2B contact data decay post covers how fast that drifts.
- Catch-all domains. A server that accepts every address can't confirm any of them. Whether a vendor counts those as accurate isn't stated. See should you send to catch-all emails.
- Your copy. A CSV you exported doesn't update when the vendor's record does. ZoomInfo's daily updates don't reach a file sitting in your drive.
Get your own number in an hour
- Export a random 300 rows from the source, not the first 300. The email list sampler pulls a random sample from any CSV.
- Verify the sample. Paste it into the verify page; the first 100 checks are free with a Google sign-in.
- Read three shares: invalid (would bounce), risky (catch-all, role, or the server wouldn't say), and valid.
- Repeat for each source you're comparing, on the same filters. The same ICP from two vendors is a fair test; two different ICPs is not.
- Decide per source. A source whose sample comes back with a high invalid share costs you twice: once in credits and again in bounces. Our test a new lead source post has the full method.
Before you trust any vendor's claim
- Ask what the figure measures and when it was last measured. Our questions to ask a B2B data vendor post lists the rest.
- Read what you're refunded when an email turns out bad. Our bounce credit refunds post compares the published terms.
- Re-verify an export right before the send, however good the source.
Where SimpleVerifier fits
SimpleVerifier doesn't sell contact data and doesn't publish an accuracy percentage for its own checks. It tells you, for each address in your export, whether the mailbox exists today, whether the domain is catch-all, and whether it's a role or disposable address. The first 100 checks are free with a Google sign-in on the verify page. Pro is $39 a month with the first 100,000 checks a month at full speed, then slower, never cut off. One-time packs of 10,000 checks for $15 never expire (CSV only). See pricing.
Common questions
Is ZoomInfo email data accurate?
ZoomInfo's email verification page says its contact data is verified at over 95% accuracy and that emails are updated daily as people change roles. It does not say how that figure is measured. Verify a sample of your own export to get a number for your market.
Which lead database has the most accurate emails?
There is no independent, published comparison we can point to. The vendors' figures are their own claims, made with methods they don't publish. Run the same 300-row test on each source you're considering and compare the invalid and risky shares.
Does a 95% accuracy claim mean a 5% bounce rate?
Not necessarily. The vendors don't say whether 95% means delivered, valid at an SMTP check, or correct person at the company. A bounce rate also depends on how old your export is and how many catch-all domains are in it.
Should I verify emails from a lead database that says they're verified?
Verify the export close to the send. Every vendor's check describes the day it ran; people change jobs and mailboxes close after that. Re-checking only costs a fraction of the credits you paid for the contacts.
Check your list before you send
Real mailbox checks over SMTP, and nothing is sent to the address. Sign in with Google and your first 100 email checks are free, no card. Plans for bigger lists are on the pricing page.