Apollo.io is one of the most widely used B2B prospecting platforms. Its database of contacts, companies, and email addresses powers outbound sales programmes at thousands of companies. It is excellent at finding email addresses. It does not guarantee those addresses are currently deliverable.
The reason is structural. Apollo builds its database by crawling the web, enriching from data partners, and aggregating from multiple sources. The database is updated regularly but not in real time. An address that was valid when last crawled may have expired since. The contact may have changed jobs. The company may have migrated email systems. The specific email format may no longer exist at that domain.
Independent testing across Apollo exports consistently shows 10 to 25% invalid address rates on unverified lists, depending on the industry segment and how recently the contacts were last updated in Apollo’s database.
Why Apollo Data Needs External Verification
Apollo is transparent about this. Their email verification is database-time verification; they check addresses when they add or update them in their database. By the time you export and use those addresses, time has passed. Sometimes days. Often weeks or months.
B2B email addresses at corporate domains expire primarily through job changes. When a contact leaves Company A, their Company A email is typically deactivated within 30 to 90 days. Apollo’s database may not reflect this change immediately. When Apollo last crawled the contact, they were at Company A with a valid email. When you export them today, they may have moved on.
The most common Apollo data quality issue is stale contact data: contacts who have changed roles or companies since their data was last updated. Invalid email rates are higher for:
- Technology sector contacts (high job turnover rates)
- Senior-level contacts (more frequent role changes)
- Contacts at startups or fast-growth companies (higher staff churn)
- Data that has not been accessed or refreshed recently in Apollo
The Risk of Skipping Verification on Apollo Lists
Cold email domains are particularly vulnerable to verification gaps. Unlike marketing email domains with years of positive engagement history, cold outreach domains are often new or moderately warmed. They have limited reputation buffer.
When a cold email domain sends to 20 to 25% invalid addresses on an Apollo export, the hard bounce rate immediately exceeds the 2% threshold that triggers reputation damage. On a new outreach domain, a single batch send to an unverified Apollo list can inflict reputation damage that requires weeks to repair, during which the domain cannot be used for outreach at its intended volume.
The economics are clear: Apollo exports at a higher price point. The contacts represent significant sourcing investment. Verification at $0.003 to $0.008 per contact protects that investment by ensuring the contacts are actually contactable.
The Verification Workflow for Apollo Exports
Step 1: Export from Apollo
In Apollo, create your search with your target company, title, and location filters. Export the results as a CSV. Include: Email, First Name, Last Name, Company, Title, Company Size, and Industry. The company and industry fields are useful for post-verification analysis; you can examine invalid rates by industry to understand which segments have the worst data quality.
Step 2: Upload to BounceProof
Go to bounceproof.co. Click Bulk Verify. Upload the Apollo export CSV. Select the email address column. Start verification.
Processing time for typical Apollo exports:
- 500 contacts: 5 to 15 minutes
- 2,000 contacts: 15 to 30 minutes
- 10,000 contacts: 30 to 90 minutes
Step 3: Review the summary
Before downloading individual results, check the summary. Note the invalid rate, catch-all rate, and any industry patterns in the results.
An invalid rate above 20% on a fresh Apollo export is a signal that either the specific segment you targeted has high turnover, or the Apollo data for that segment is not recently refreshed. Investigate before continuing to source from the same criteria.
Step 4: Download and filter results
Download the classified results CSV. Filter to valid addresses for your primary sequence. Separate catch-all results for risk-based handling. Suppress invalid and disposable addresses from all sequences permanently.
What to Do With Each Result Type
Valid (include): These addresses passed SMTP verification. Safe to include in your cold email sequences. Load them into your sequencer as your primary outreach audience.
Invalid (suppress permanently): Do not attempt outreach to these addresses. Flag them in Apollo if your Apollo plan supports contact tagging. This helps Apollo’s data quality feedback loop and prevents you from re-exporting the same invalid contacts in future searches.
Disposable (suppress): Extremely rare in B2B Apollo exports but possible if contacts provided disposable addresses for form fills that Apollo scraped. Suppress permanently.
Catch-all (apply risk management): See the next section for detailed catch-all handling specific to Apollo exports and cold outreach domains.
Unknown (re-verify after 48 hours): Corporate mail servers sometimes rate-limit or time out verification probes. Re-run these after 48 hours. Most will resolve to valid or invalid on the second pass.
Integrating Verification Into Your Apollo-to-Sequencer Pipeline
Most outbound teams follow this pipeline: Apollo search → export CSV → import to sequencer (Instantly, Smartlead, Lemlist). Verification fits between export and import.
Manual workflow (for occasional exports):
Apollo export → BounceProof upload → download results → filter to valid → import to sequencer
Automated workflow (for frequent exports):
Using Clay: Add a BounceProof API step to your Clay table. When a new row is added from Apollo, Clay triggers the verification API call and writes the result to a “verified_status” column. Only rows with verified_status = “valid” continue to the sequencer row. This eliminates the manual export-verify-import cycle.
Using Zapier/Make: Apollo export triggers a webhook that runs through BounceProof’s API. Results write to a Google Sheet. Sequencer import pulls only from the verified-valid rows.
The automated pipeline adds 2 to 5 minutes of processing per contact batch and eliminates the risk of sequences starting before verification is complete.
Catch-All Handling for Apollo B2B Data
Apollo exports from corporate domains frequently include catch-all addresses. Many mid-size companies configure their mail servers to accept all incoming email, making SMTP verification ambiguous for those specific mailboxes.
For cold email sequences on new or moderately warmed domains:
Exclude all catch-all addresses from new domain sequences. New outreach domains (less than 90 days old or still in warm-up) have insufficient reputation buffer to absorb the delayed bounce risk from catch-all addresses where the mailbox may not exist.
Include high-confidence catch-all on established domains. If your outreach domain has been running for 6+ months with clean sending history and Google Postmaster Tools shows High reputation, include BounceProof’s high-confidence catch-all addresses (confidence score above 70) in your sequences. Monitor their bounce rate in a separate segment.
Always separate catch-all into its own sequence. Do not mix catch-all and verified-valid contacts in the same sequence. Separate tracking lets you monitor catch-all bounce rates independently and pause the catch-all sequence if bounce rate climbs above 2% without affecting your main valid-address sequence.
How Often to Re-Verify Apollo Contacts
Within 24 hours of first sequence email: Verify within 24 hours of when you plan to send the first email in any sequence. Not when you export from Apollo, but when you are about to send. Addresses can become invalid in the gap between export and sequence start, particularly for contacts at high-turnover companies.
Every 30 days for contacts not yet contacted: If you built a list in Apollo and have not reached the contacts yet, re-verify after 30 days. A contact exported on June 1 who was not contacted until July 1 should be re-verified before the first sequence email; a month is enough time for a corporate address to be deactivated.
After significant batch adds: When you add a large batch of Apollo contacts to an ongoing sequence, verify the new batch separately from contacts already in the sequence. Do not assume contacts added from the same Apollo search criteria have the same validity rate as your initial export.
Frequently Asked Questions
Yes, Apollo verifies emails when they enter its database, but that verification can become outdated over time.
Mixed-industry exports can have invalid emails, especially when data has not been updated recently.
For bulk exports, external verification can provide deeper checks such as catch-all, disposable, and detailed status results.
Apollo confidence reflects its database assessment, while BounceProof checks the address against the current mail server.
Yes. Reverify older exports before sending campaigns because email addresses can become inactive over time.
Conclusion
Apollo is an excellent prospecting tool. The email addresses it surfaces are found through rigorous crawling and enrichment. They are not always currently deliverable.
The 20 to 30 minutes to verify each Apollo export before loading into a sequence is the most important step in your outbound workflow. It protects your sending domains from the bounce damage that unverified exports predictably cause. It ensures the sequences you build are reaching real, active inboxes rather than generating hard bounces that erode the domain reputation your entire outbound programme depends on.
Verify before the first email. Every time. No exceptions.
