Blacklists and whitelists

What are blacklists and whitelists?

In the world of the Internet, a "blacklist" is an access control mechanism - a way to indicate that "everyone except members of the blacklist is allowed." A whitelist has the opposite function: "no one is allowed except members of the whitelist."

(A "greylist" functions as a sort of middle ground or temporary blacklist. For example, it can be used to block poorly-configured email clients that may be used to send spam.)

Many organizations maintain a blacklist of undesirable software or Web sites in their computer systems. This list might include pornographic Web sites, other sites that are inappropriate for children, and Web/email servers that are known to send spam. Emails sent from blacklisted servers wil be prevented from reaching their intended recipients; instead, such emails are usually diverted to a "junk" or "spam" repository.

Email servers that are used to send very large numbers of marketing emails are often blacklisted if they do not use opt-in marketing lists.

ThinkSend diligently monitors various blacklists to ensure that our email deployment servers are not blacklisted. In fact, our delivery servers are usually whitelisted because of our stringent opt-in permission policies.

For more information, please visit our Deliverability and Support page.