Email Append
The practice of adding email addresses to existing customer or contact records using third-party data sources.
Email append is a data enrichment service where a business provides a list of customer records (typically name + postal address or phone number) to a data provider, who matches those records against their database to find and append corresponding email addresses. The goal is to add an email communication channel to contacts you already have a relationship with but lack an email for.
How email append works: 1. You upload a file with customer names and physical addresses (or phone numbers) 2. The append provider matches your records against their database of known name-email associations 3. Matched emails are returned to you, typically with a match rate of 20-40% 4. You should verify all appended emails before sending, since data quality varies by provider
Risks and best practices:
- Always verify appended emails — match quality varies widely and sending to invalid appended addresses damages your reputation
- Use permission-based sending — just because you have someone's email doesn't mean they consented to marketing from you
- GDPR/CCPA implications — appending emails to EU/California residents requires a legitimate interest basis and proper privacy notices
- Start with a welcome email — introduce yourself and provide a clear unsubscribe option before launching into marketing campaigns
- Run all appended lists through SendSure to remove invalid, disposable, and risky addresses before your first send
Related terms
Email Verification
The process of confirming whether an email address is valid, deliverable, and belongs to a real person.
Email Hygiene
The set of practices used to maintain a clean, healthy email list by removing invalid, inactive, and risky addresses.
Double Opt-In
A two-step email subscription process where the user must confirm their signup by clicking a link in a verification email.
Want to learn more?
Blog posts on verification and deliverability.