How to Verify Emails for Instantly, Smartlead, and Lemlist (Before You Upload)

Filter on email_status before you export. The CSV you upload then holds only addresses you will send to. The three tools import differently, but the pre-send check is the same.

Related: how to verify email addresses, the best email finder for Smartlead, the best email finder for Lemlist and pricing.

TL;DR

• Every LeadOcean person record carries an email_status. Filter to verified and export, so bad addresses never reach your sending domains.
• Takes about 20 minutes. The test run here spends 100 records. Counting and sizing the list spends none.
• The free plan has 1,000 records for life, no card, so you can run this guide as written.

Prerequisites

• A LeadOcean API key from app.leadocean.io, exported as $LEADOCEAN_API_KEY. A key on the free plan has the search and enrich scopes.
• curl and Python 3.
• An account in the sequencer you use: Instantly, Smartlead or Lemlist. Any of the three takes a CSV.

Bulk CSV export is not on the free plan. On Free, run the Step 2 filters through POST /v1/people/search with limit 100, then enrich each person_id with reveal_email: true to get the address. Search rows carry the status but not the address, so that route spends a record per row and per enrichment. Or move to Solo at $97 a month.

Step 1: Size the list for free

Count first. A count call costs 0 records and tells you how many verified people match before you spend anything. Send count=true as a query parameter, not in the JSON body, with limit 1.

curl -X POST "https://api.leadocean.io/v1/people/search?count=true&limit=1" \
  -H "x-api-key: $LEADOCEAN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"jobLevel":["VP"],"country":["US"],"emailStatus":["verified"]}'

data comes back empty and meta.countOnly is true. meta.total is capped at 100,000 on this call, so for a broad query use the MCP tool leadocean_count_leads instead. It gives an exact total and a breakdown. Enum values are exact strings: VP, not vp. List them with leadocean_list_enum_values.

Step 2: Export only the statuses you will send to

Choose your cutoff once. verified is the strict list. Add catch_all_valid if you accept domains that accept all mail but passed a further check. Leave catch_all, risky, unknown and untested out of the first send.

curl -X POST https://api.leadocean.io/v1/exports \
  -H "x-api-key: $LEADOCEAN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "sequencer upload",
    "filters": {
      "jobLevel": ["VP"],
      "country": ["US"],
      "emailStatus": ["verified"]
    },
    "limit": 100,
    "columns": ["person_id","profile_full_name","current_company_domain","email_N_address","email_N_status"]
  }'

The answer is a 202 with a job id. An export spends one record per row. A request takes up to 50,000 rows and a day takes up to 500,000.

Which status to send to

Each status is a different bet. The values below are the ones LeadOcean returns for email_status.

The default for a LeadOcean count is verified, catch_all_valid and catch_all. Set emailStatus yourself so your count matches your cutoff. A count with an emailStatus filter is a count of people at those statuses. It is not a promise of delivery.

Step 3: Poll the job and download the CSV

curl -H "x-api-key: $LEADOCEAN_API_KEY" https://api.leadocean.io/v1/exports/EXPORT_ID
curl -H "x-api-key: $LEADOCEAN_API_KEY" -o leads.csv \
  https://api.leadocean.io/v1/exports/EXPORT_ID/download

Poll the first call until data.status is done. The status call is free. The CSV headers come back as email_1_address and email_1_status, even though you asked for email_N_*.

Step 4: Add a last gate before the upload

The filter already did the work. This script is a belt-and-braces check on the file: it drops blank addresses and anything that is not verified, and writes one CSV for the sequencer.

import csv

ok = {"verified"}   # add "catch_all_valid" if you accept it
rows, dropped = [], 0
with open("leads.csv", newline="") as f:
    for r in csv.DictReader(f):
        if r["email_1_address"] and r["email_1_status"] in ok:
            rows.append({
                "email": r["email_1_address"],
                "full_name": r["profile_full_name"],
                "company_domain": r["current_company_domain"],
                "person_id": r["person_id"],
            })
        else:
            dropped += 1

with open("sequencer_upload.csv", "w", newline="") as f:
    w = csv.DictWriter(f, fieldnames=["email","full_name","company_domain","person_id"])
    w.writeheader()
    w.writerows(rows)

print(f"kept {len(rows)}, dropped {dropped}")

Keep person_id. It lets you suppress or re-check one person later without searching again.

Step 5: Upload to your sequencer

Upload sequencer_upload.csv through the CSV lead import of the tool you use. Map the email column to the tool's email field. Map the rest to custom fields, or skip them. Import screens differ by tool and plan, so follow each tool's own import docs rather than a fixed menu path.

LeadOcean does not send email and does not warm inboxes. It supplies the list. The sequencer owns sending.

Step 6: Re-check the catch-alls (optional)

Catch-all domains accept any address, so no checker can be certain about them. If you want to send to them anyway, export the catch_all rows separately and run them through a dedicated verifier first. LeadOcean + VerifyHQ shows that route with a script. Send the catch-alls from a separate sub-campaign so a bounce spike is easy to trace.

Run this check before every upload

The recipe repeats well. Keep the same five habits each time you build a list.

• Count first, with your exact emailStatus cutoff. Write the cutoff down so a teammate can repeat it.
• Export with person_id in the columns. It is your join key for suppression lists and re-checks.
• Read email_1_status on the file you receive, not just the filter you sent. The script in Step 4 does this in one pass.
• Start small. Send 100 to 200 rows first and read the bounce rate in your sequencer before the full list goes out.
• Re-export lists older than a month. The dataset is refreshed monthly, so an old CSV drifts.

Keep catch-alls and verified rows in separate campaigns. When bounces rise, you will know which batch caused it.

What you get

This is a free count run through the MCP tool leadocean_count_leads on 2026-10-21. It costs 0 records.

{
  "filters": { "jobLevel": ["VP"], "country": ["US"], "emailStatus": ["verified"] },
  "total": 257840,
  "totalIsExact": true,
  "distinctCompanies": 83722,
  "distinctCompaniesIsExact": false,
  "credits": 0
}

That is the count of US VPs whose email status is verified. It is not a count of people who will answer. The export in Step 2 returns a CSV like this. It is the response shape from the API reference, with placeholder values.

person_id,profile_full_name,current_company_domain,email_1_address,email_1_status
1234567890,Jane Doe,acme.com,jane.doe@acme.com,verified

Troubleshooting

The limits are listed on the LeadOcean limits docs, checked September 2026.

FAQ