Whitelist

A whitelist is exactly the opposite of a blacklist. As a noun, whitelist has become a generic term for either an email and/or IP address that has proven themselves as trusted source. Users as well as providers can compile and use these lists to ensure greater Internet safety and reliability. As a verb, it is used to describe the act of adding an email or IP to a list of accepted senders.

Simple and effective, including filters based on both blacklist and whitelist metrics for filtering and approving messages for delivery instead of trying to keep up with an ever-growing list of banned or suspect IP addresses just makes more sense. In this way wanted messages get through, but in no way is a fail-safe method. To ensure greater reliability, both lists have to be continually updated with new email addresses, keywords, or other data triggers.

There are both commercial and non-commercial whitelists, of which both have certain requirements for inclusion or rejection. For the non-commercial list an ISP must have a static IP address and not be an open relay. At anytime the whitelist owner receives complaints or reports of spam from that source they can and will remove that source from their list. In the case of commercial whitelists, these are obtained by the source paying a fee, and ensures that messages will be delivered as intended. The three most used as of 2010 are; Good Mail System’s Certified Email, Return Path Certification, Eco’s Certified Senders Alliance, and Spamhaus Whitelist and in most cases provide administrative control and help to prevent any introduction of new forms of malware.