Also called “e-append,” this is an email marketing practice where the known customer data is matched against a vendor’s database to extract their email addresses. In this case, the customer data include a postal address, last name, and first name. It is not considered an email best practice because it doesn’t involve express opt-in permission.
Email Append can be defined as “the process of adding a consumer’s email address to that consumer’s record. The email address is obtained by matching those records from the marketer’s database against a third-party database to produce a corresponding email address” – the Association of National Advertisers (ANA) Guidelines for Ethical Business Practice: Digital Marketing.
While this is the widely-circulated definition, there is more to email append than you can deduct from here. While you get more updated and comprehensive information about customers by running your current database against an external database from a vendor, email append also allows you to include fields like marital status, income, age, and more.
So, it is safe to conclude that email append upgrades your database from being a simple list of contacts into a list of real individuals.
Reverse Email Append
It is important not to mix this up with the regular email append. Reverse email append means matching your present customer email address against the database from a data provider (for instance, DeBounce). The purpose of this matching is to get important information about your customers, such as their full names, addresses, and more.