Bulk Email Verification: Clean 10,000+ Email Lists Fast

Sending to a dirty email list destroys your sender reputation. A bounce rate above 5% can get your domain blacklisted. Here's how to clean any size list quickly using the CheckMail1 API.

Why Bulk Verification Matters

• Hard bounces above 2% hurt deliverability with Gmail and Outlook
• Invalid emails waste sending credits
• Spam traps hidden in old lists can blacklist your domain
• Catch-all domains inflate your list with unverifiable addresses

Bulk Verify with Python

import requests, csv

API_KEY = "your_api_key"
results = []

with open("emails.csv") as f:
    for line in f:
        email = line.strip()
        r = requests.get(
            f"https://checkmail1.com/api/verify?email={email}",
            headers={"Authorization": f"Bearer {API_KEY}"}
        )
        data = r.json()
        results.append({
            "email": email,
            "valid": data.get("valid"),
            "reason": data.get("reason")
        })
        
# Keep only valid emails
valid = [r["email"] for r in results if r["valid"]]
print(f"Valid: {len(valid)} / {len(results)}")

Batch API (Up to 10 at Once)

curl -X POST https://checkmail1.com/api/verify/batch \
  -H 'Authorization: Bearer YOUR_API_KEY' \
  -H 'Content-Type: application/json' \
  -d '{{"emails":["user1@gmail.com","user2@yahoo.com","user3@outlook.com"]}}'