Definition
Email harvesting — also known as email scraping or address harvesting — is the automated collection of email addresses from publicly accessible online sources using software bots. Harvesters crawl websites, forums, social media profiles, comment sections, and any other pages where email addresses appear to extract and compile addresses into databases.
Harvested email lists are sold to spammers and unethical marketers. Emailing harvested addresses is illegal under CASL and GDPR, violates CAN-SPAM if the email is commercial and the sender has no relationship with the recipient, and results in extremely high bounce rates and spam complaints that destroy sender reputation.
Common Harvesting Methods
| Method | Source | How It Works |
|---|---|---|
| Web scraping | Websites, directories | Bots extract text matching email patterns |
| Forum crawling | Discussion boards, comments | Collects addresses from public posts |
| WHOIS lookup | Domain registration data | Extracts email from public WHOIS records |
| Dictionary attacks | ESP domains | Generates common email patterns (info@, sales@) |
| Data breaches | Compromised databases | Purchases stolen email databases |
Best Practices
- Never purchase or use harvested email lists — they violate laws and ESP terms
- Protect your website email addresses with obfuscation techniques (e.g., contact forms instead of mailto links)
- Use CAPTCHA on sign-up forms to prevent automated collection
- Monitor your list for signs of harvested addresses (unusual bounce patterns)
- Report email harvesting to the relevant platform or hosting provider
- Educate stakeholders about the legal and reputational risks of purchased lists
Related Glossary Terms
Subscriber Acquisition
Subscriber acquisition is the process of gaining new email subscribers through organic, paid, and partnership channels, directly impacting list growth rate and quality.
Email Appending
Email appending is the practice of adding email addresses to an existing contact database using a third-party service, typically by matching known contact data against a vendor's email database — a risky practice that often damages sender reputation.
Email Audience Growth
The economics and strategy of growing an email subscriber list, including growth rate analysis, channel performance comparison, and growth versus retention ROI.
Email Co-Registration
Co-registration marketing collects email addresses through partner brand signup forms, requiring clear disclosure and data sharing agreements with typical conversion rates of 1 to 5 per cent.
List Building Ethics
List building ethics guides the moral and legal standards for acquiring email subscribers, ensuring consent is informed, voluntary, and respectful of recipient rights.
List Building Strategies
List building strategies are tactical approaches to growing an email subscriber base through content upgrades, partnerships, social media, SEO, and paid acquisition.
Frequently Asked Questions
Email harvesting itself occupies a legal grey area in many jurisdictions, but using harvested addresses to send commercial email violates anti-spam laws in most countries. CAN-SPAM (US) does not explicitly prohibit harvesting but does prohibit sending to harvested addresses. CASL (Canada) and GDPR (EU/UK) explicitly prohibit sending commercial email without consent.
Signs include an unusually high hard bounce rate (above 10%), a high spam complaint rate from the first send, recipients who have no knowledge of your brand, and role-based email addresses (info@, admin@, sales@) with no other identifying data. Legitimate subscribers typically provide additional information beyond just an email address.