A spam filter is a software application that runs on a POP3/IMAP mail server and monitors all incoming emails so as to prevent any unrequested ones from entering a particular inbox. Several instances of such email messages would be: offers for pills or money, false bank statements or attachments that contain malicious software sent with the idea of infecting your PC. Spam filters usually ‘scan’ the content of an email and if they detect specific keywords or other suspicious content, they either erase the email or deliver it to the Junk/Spam folder instead of the Inbox folder. Certain hosting companies combine their own filters with up-to-the-minute databases from spam-detecting organizations, so as to guarantee higher levels of protection for their clients. Such databases include patterns, mail server IP addresses and other info about spam email messages recently uncovered by these organizations.