How to Use Email Verification in Python (Complete Guide)

Whether you're building a SaaS app, a data pipeline, or an email marketing tool, adding email verification in Python is straightforward. Here's everything you need.

Basic Syntax Validation

import re

def is_valid_format(email):
    pattern = r'^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$'
    return bool(re.match(pattern, email))

print(is_valid_format('[email protected]'))  # True
print(is_valid_format('notanemail'))      # False

API-Based Verification

For real verification (checking if the mailbox exists), use the CheckMail1 API:

import requests

API_KEY = 'your_api_key_here'

def verify_email(email):
    response = requests.get(
        'https://checkmail1.com/api/verify',
        params={'email': email},
        headers={'X-API-Key': API_KEY}
    )
    return response.json()

result = verify_email('[email protected]')
print(result)
# {'valid': True, 'score': 95, 'provider': 'gmail'}

Bulk Verification

from concurrent.futures import ThreadPoolExecutor
import csv

def verify_bulk(email_list, max_workers=10):
    with ThreadPoolExecutor(max_workers=max_workers) as executor:
        results = list(executor.map(verify_email, email_list))
    return results

# Load from CSV
with open('emails.csv') as f:
    reader = csv.reader(f)
    emails = [row[0] for row in reader]

results = verify_bulk(emails)
valid = [e for e, r in zip(emails, results) if r.get('valid') and r.get('score', 0) > 70]
print(f'{len(valid)}/{len(emails)} valid emails')

Adding to Django or Flask

# Flask example
from flask import request, jsonify

@app.route('/register', methods=['POST'])
def register():
    email = request.json.get('email')
    result = verify_email(email)
    if not result.get('valid') or result.get('score', 0) < 70:
        return jsonify({'error': 'Invalid email address'}), 400
    # proceed with registration
    return jsonify({'success': True})

Get your free API key (100 verifications included) at checkmail1.com.