Overview
A whitelist or allowlist is a list or register of entities that are being provided a particular privilege, service, mobility, access or recognition. Entities on the list will be accepted, approved and/or recognized. Whitelisting is the reverse of blacklisting, the practice of identifying entities that are denied, unrecognized, or ostracized.
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Email whitelists
Spam filters often include the ability to "whitelist" certain sender IP addresses, email addresses or domain names to protect their email from being rejected or sent to a junk mail folder. These can be manually maintained by the user or system administrator - but can also refer to externally maintained whitelist services.
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Non-commercial whitelists
Non-commercial whitelists are operated by various non-profit organizations, ISPs, and others interested in blocking spam. Rather than paying fees, the sender must pass a series of tests; for example, their email server must not be an open relay and have a static IP address. The operator of the whitelist may remove a server from the list if complaints are received.
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Commercial whitelists
Commercial whitelists are a system by which an Internet service provider allows someone to bypass spam filters when sending email messages to its subscribers, in return for a pre-paid fee, either an annual or a per-message fee. A sender can then be more confident that their messages have reached recipients without being blocked, or having links or images stripped out of them, by spam filters. The purpose of commercial whitelists is to allow companies to reliably reach their customers by email.
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Advertising whitelist
Many websites rely on ads as a source of revenue, but the use of ad blockers is increasingly common. Websites that detect an adblocker in use often ask for it to be disabled - or their site to be "added to the whitelist" - a standard feature of most adblockers.
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The source notesEvidence & further reading4 sources
- Whitelist — Wikipedia, revision 1367809898 Wikipedia contributors · Reference source · accessed 2026-09-22
- "IP and domain reputation". Spamhaus Project. spamhaus.org · Reference source · link imported 2026-09-22
- "Spamhaus' Blocklists". spamhaus.org · Reference source · link imported 2026-09-22
- "Adblock Instructions". Forbes. Retrieved 2017-12-09. forbes.com · Reference source · link imported 2026-09-22
Selected and reformatted from Whitelist, by its contributors, under CC BY-SA 4.0. Revision 1367809898. Sections and formatting have been shortened; the linked revision provides the full context and contributor history. This reference text remains under the same license. Its additional citation links are imported from that revision and have not been independently checked here.