Anti-spam programs can detect unwanted email and prevent it from reaching users’ inboxes.
These programs use a combination of methods to decide whether an email is likely to be
spam. They can:
- Block email that comes from computers on a blocklist. This can be a commercially available list or a local list of computer addresses that have sent spam to your company before.
- Block email that includes certain web addresses.
- Check whether email comes from a genuine domain name or web address.
Spammers often use fake addresses to try to avoid anti-spam programs.
- Look for keywords or phrases that occur in spam (e.g., “credit card,” “lose weight”).
- Look for patterns that suggest the email’s sender is trying to disguise his or her words (e.g., “hardc*re p0rn”).
- Look for unnecessary HTML code (the code used for writing webpages) used inemail, as spammers often use this to try to conceal their messages and confuse antispam programs.
- The program combines all the information it finds to decide the probability of an email being spam. If the probability is high enough, it can block the email or delete it, depending on the settings you choose.
Anti-spam software needs frequent updating with new rules that enable it to recognize the latest techniques used by spammers.