A blacklist is a list of items in a set that are not accepted. In computer security, a blacklist may be used to exclude which set to detect, quarantine, block, or perform security scans on. This list is exclusionary, confirming that the item being analyzed is not acceptable. It is the opposite of a whitelist, which confirms that items are acceptable. An email blacklist, for example, would not allow email from specific email addresses—such as ones that are known to be malicious—to be received.