Anti-spam refers to software, technique, or hardware designed to keep accounts and devices protected from spam. With a general focus on email security, anti-spam can get better at detecting and removing any harmful links or files including phishing emails and intrusive sales letters.

Real anti-spam examples

  • Challenge/response systems: Here, the sender is required to execute an action for the message to be delivered. These random tasks can be CAPTCHA, which is fairly easy for humans but impossible for automated tools. 
  • DNS disallow lists: In this variant, a list comprising every IP address linked to spam content and made available to the public. This list is known as a DNS allow list or DNSBL). Now, email servers can query such lists before accepting a message, enabling them to reject spam messages faster and more accurately. 
  • URL filtering: Many spam messages will come with some link you need to click. Don’t click it. With URL filtering however, the anti-spam service can check if the link belongs to any spam databases. Once it is ascertained that it is indeed spam, the message will be deleted.