Email appending, also known as e-appending, is a marketing practice that involves taking known customer data (first name, last name, and postal address) and matching it against a vendor's database to obtain email addresses. The purpose is to grow one's email subscriber list with the intent of sending customers information via email instead of through traditional mail. Email appending is a controversial practice in the email marketing world, with critics claiming that sending email to people who never explicitly opted-in is against best practices.
An email appending process involves either a business or consumer database made up of contacts including their name, address and company name [for business contacts]. If the company wants to expand into email communication, then they can involve a service provider that has a database of email addresses in order to merge the data together and append business or consumer email addresses to their existing file. In this way they can have an updated database with the current email address of individuals on the list. The success of email appending depends on the quality of both databases being merged.
Mail sent by email appending methods can be either opt-out or opt in email. Vendors that use opt-in methods send an initial permission based email to the appended email addresses asking customers if they would like to opt into the client's mailing list in addition to giving them the opportunity to unsubscribe.
In September 2011, The Messaging Anti-Abuse Working Group (MAAWG) released a position paper stating the practice of email appending is in direct violation to their values and is an abusive practice.