An email filter is a software application that’s installed on a POP3/IMAP server and keeps track of all inbound email messages to stop any unwelcome ones from entering a particular inbox. Several examples of such emails would be: offers for pills or cash, fraudulent bank notices or attachments that contain malicious code sent with the intention of infecting your personal computer. Spam filters usually examine the content of an email message and when they spot specific keywords or other suspicious content, they either delete the email or deliver it to the Junk/Spam folder instead of the Inbox folder. Some web hosts mix their own email filters with up-to-the-minute databases from spam-detecting organizations, so as to ensure better protection for their customers. Such databases contain patterns, email server IP addresses and other information about spam email messages recently uncovered by these organizations.