An email filter is a software application that is installed on a POP3/IMAP server and monitors all inbound emails so as to impede any undesired ones from entering a particular mailbox. Several instances of such emails would be: offers for pills or cash, fraudulent banking notices or attachments that contain malicious software sent with the idea of infecting your computer. Spam filters typically check the content of an email message and when they come across some keywords or other suspicious content, they either delete the email message or deliver it to the Spam/Junk folder instead of the Inbox folder. Certain providers combine their own email filters with up-to-the-minute databases from spam-tracking organizations, so as to ensure higher levels of security for their clients. Such databases contain patterns, email server IP addresses and other info about spam emails recently reported by these organizations.