We Validated 10,000 Apollo Contacts: Here's What We Found
Last month we pulled 10,000 contacts from Apollo.io and ran every single one through three-layer email validation. Not a sample. Not a subset. All 10,000.
Apollo claims 91% email accuracy. Our results told a different story.
22% of those contacts were undeliverable. Another 14.6% landed in the risky gray zone. That means over a third of the list couldn’t be trusted to reach a real inbox.
Here’s the full breakdown.
Methodology
We exported 10,000 contacts from Apollo across five B2B verticals: SaaS, financial services, healthcare, manufacturing, and professional services. All contacts had Apollo’s “Verified” or “Likely to Engage” status tags. We intentionally excluded contacts Apollo marked as “Unverified” or “Update Required” because most SDRs already skip those.
Every address went through MailCop’s three-layer verification: syntax check, MX record lookup, and live SMTP handshake. We ran the full validation within 48 hours of export to minimize decay bias.
We didn’t cherry-pick bad data. We didn’t stack the deck with old contacts. These were fresh exports filtered to Apollo’s own recommended sending statuses.
Overall Results
Here’s what came back.
| Validation Status | Count | Percentage |
|---|---|---|
| Deliverable | 5,840 | 58.4% |
| Undeliverable | 2,200 | 22.0% |
| Risky / Catch-All | 1,460 | 14.6% |
| Unknown | 500 | 5.0% |
58.4% deliverable. That’s it. From a list Apollo labeled as verified.
If you’d loaded those 10,000 contacts straight into Instantly or Lemlist, you’d be sending to 2,200 dead addresses on day one. At that volume, you’re looking at a 22% bounce rate. Google starts throttling at 2%. You’d burn your sending domain before the first sequence finishes.
Breakdown by Industry
Not all verticals performed equally. Some were far worse than others.
| Industry | Contacts | Deliverable | Undeliverable | Risky | Unknown |
|---|---|---|---|---|---|
| SaaS | 2,000 | 62.5% | 19.0% | 13.5% | 5.0% |
| Financial Services | 2,000 | 56.0% | 24.5% | 15.0% | 4.5% |
| Healthcare | 2,000 | 51.5% | 27.0% | 15.5% | 6.0% |
| Manufacturing | 2,000 | 60.0% | 21.0% | 14.0% | 5.0% |
| Professional Services | 2,000 | 62.0% | 18.5% | 15.0% | 4.5% |
Healthcare was the worst performer at 51.5% deliverable. Makes sense. Hospital systems and medical groups churn IT infrastructure constantly, and HIPAA compliance leads to aggressive mailbox deactivation policies. Financial services wasn’t far behind at 56%.
SaaS and professional services performed best, but “best” still means nearly 1 in 5 addresses were dead on arrival.
Breakdown by Seniority Level
We tagged each contact by seniority using Apollo’s title data. Who bounces more, the CEO or the SDR?
| Seniority | Contacts | Deliverable | Undeliverable |
|---|---|---|---|
| C-Suite | 1,200 | 53.0% | 26.5% |
| VP | 1,800 | 55.5% | 24.0% |
| Director | 2,500 | 59.0% | 21.5% |
| Manager | 2,800 | 61.5% | 19.5% |
| Individual Contributor | 1,700 | 63.0% | 18.0% |
The higher the title, the worse the deliverability. C-suite contacts bounced at 26.5% compared to 18.0% for individual contributors. Senior executives change roles more frequently, use executive assistants who manage separate inboxes, and often have legacy addresses that persist in databases long after they’ve moved on.
If you’re running ABM campaigns targeting VPs and above, you’re working with the least reliable segment of Apollo’s data. Exactly the contacts you can least afford to bounce.
Catch-All Domain Prevalence
14.6% of addresses landed in the risky/catch-all bucket. But the distribution wasn’t even across company sizes.
| Company Size | Catch-All Rate |
|---|---|
| 1-50 employees | 22.3% |
| 51-200 employees | 18.7% |
| 201-1,000 employees | 12.4% |
| 1,000+ employees | 8.1% |
Small companies run catch-all at nearly 3x the rate of enterprises. Smaller IT teams, simpler email configs, and the “don’t miss anything” default setting on Google Workspace all contribute.
For SDRs targeting SMBs, this means a bigger chunk of your list sits in that verification gray zone where you can’t confirm delivery without actually sending. That’s where a catch-all domain strategy becomes critical.
Role-Based and Disposable Emails
Two more categories worth flagging.
Role-based addresses (info@, sales@, support@, team@) made up 3.8% of the 10,000 contacts. That’s 380 addresses Apollo exported as individual contacts that were actually shared inboxes. Sending cold outreach to these generates spam complaints at 3-5x the rate of personal addresses. They should never make it into a cold sequence.
Disposable emails accounted for 0.9% of the total. 90 addresses from throwaway services like Guerrilla Mail and Temp Mail sitting in a B2B prospecting database. These addresses have a lifespan measured in hours. Apollo’s verification didn’t catch them.
Combined, that’s 4.7% of the list that should’ve been filtered out before export but wasn’t.
Apollo’s Accuracy vs. Our Findings
Apollo advertises 91% email accuracy. We found 58.4% deliverable. What explains the gap?
Three factors.
First, timing. Apollo verifies at enrichment time, not export time. Their database refreshes on a rolling schedule. A contact verified three months ago could’ve changed jobs, had their mailbox deactivated, or moved to a new domain since Apollo last checked. B2B email data decays at roughly 2-2.5% per month. Over a quarter, that’s 6-7.5% degradation baked in.
Second, methodology differences. Apollo’s 91% figure likely counts catch-all addresses as “verified” since the server accepts the connection. Our count treats catch-all as “risky” because the server says yes to everything. If you add our deliverable (58.4%) and risky (14.6%) categories together, you get 73%. Still well below 91%, but the catch-all classification accounts for part of the gap.
Third, Apollo’s verification depth. Their 7-step process uses pattern matching, historical data, and contributory network signals. That’s useful at scale but it’s not the same as a live SMTP handshake confirming a specific mailbox accepts mail right now. Apollo’s waterfall enrichment update in late 2025 improved things, but probabilistic matching will always lag behind direct server confirmation.
None of this makes Apollo a bad tool. It’s excellent for prospecting and list building. But treating Apollo’s “Verified” tag as a substitute for dedicated email validation is a mistake that’ll cost you sender domains.
What This Means for Your Workflow
The numbers point to one conclusion. You need a validation step between Apollo and your sending tool. Every time.
Here’s what a clean workflow looks like.
- Export from Apollo with “Verified” and “Likely to Engage” filters.
- Run the full list through MailCop’s bulk validator.
- Remove all undeliverable, role-based, and disposable addresses.
- Segment catch-all addresses into a separate campaign with lower daily volume.
- Load only validated contacts into your sequencer.
We’ve written the step-by-step version of this in our guide to cleaning Apollo exports for Instantly. If you’re running cold outreach at any real volume, that workflow should be your default.
The Cost of Skipping Validation
Quick math. If you’d sent to all 10,000 contacts without validation, you’d hit a 22% bounce rate on the first send. Google throttles at 2%. Your domain reputation drops to “bad” in Postmaster Tools within days. Recovery takes 30-90 days of clean sending. During recovery, you lose all sending capacity from that domain.
For a team sending 200 emails per day at a 3% reply rate, that’s 6 conversations per day you lose during recovery. If each positive reply is worth $50 in expected pipeline value (a conservative estimate given typical B2B deal sizes and close rates), that’s roughly $9,000 in pipeline lost per month of downtime. A 60-day recovery window costs $18,000 in missed opportunities.
Validating 10,000 addresses costs about $30-80 depending on your plan. The ROI isn’t close.
Key Takeaways
Five numbers to remember from this study.
- 22% of Apollo “Verified” contacts were undeliverable.
- 14.6% were catch-all/risky with no delivery guarantee.
- C-suite contacts bounced 47% more often than individual contributors.
- Healthcare had the lowest deliverability at 51.5%.
- 4.7% were role-based or disposable addresses that shouldn’t exist in a B2B database.
Apollo gives you the leads. It doesn’t guarantee they’ll land. Every list needs validation before it touches your sending infrastructure. No exceptions.
If you’re building your full outbound stack, the cold email deliverability playbook covers authentication, warm-up, and domain rotation alongside the validation workflow. Start there.