(1) A list of email addresses that a mail server or email client program is configured to accept as valid, incoming mail. Also called a "safe senders list," Email filtering that relies entirely on whitelists is severely restricted because only messages from addresses on the list are allowed, and all the rest are discarded. See
spam filter. Contrast with
blacklist.
(2) A list of valid domain names that a mail server is configured to accept. All mail from users with that domain are allowed. Contrast with
blacklist.
(3) A list of websites that are allowed to be accessed. A company can configure its routers and firewalls to allow only certain websites to be accessed, because they relate to business. Contrast with
blacklist.
(4) A list of applications that a user is authorized to run in an organization. Maintained by the system or network administrator, when the application is run, software in the user's computer may check the program for integrity to ensure it has not been compromised. Contrast with
blacklist.