A spam filter is a software application that is installed on a POP3/IMAP server and keeps track of all inbound messages so as to block any unwelcome ones from reaching a specific mailbox. Several examples of such emails would be: offers for pills or cash, fraudulent bank statements or attachments that contain malicious software sent with the idea to damage your personal computer. Spam filters usually examine the content of an email and if they come across given keywords or other dubious content, they either erase the email or forward it to the Junk/Spam folder instead of the Inbox folder. Certain companies combine their own spam filters with up-to-the-minute databases from spam-tracking organizations, so as to guarantee better security for their customers. Such databases contain patterns, email server IPs and other information about spam email messages recently revealed by these organizations.