An email filter is a software app that runs on a POP3/IMAP mail server and monitors all incoming email messages to obstruct any unwanted ones from entering a specific mailbox. A few instances of such email messages would be: offers for pills or cash, fraudulent bank notifications or attachments that contain malicious code sent with the intention of infecting your personal computer. Email filters normally ‘scan’ the content of an email message and in case they come across given keywords or other suspicious content, they either delete the email message or re-send it to the Spam/Junk folder instead of the Inbox folder. Some companies mix their own spam filters with up-to-date databases from spam-tracing organizations, so as to guarantee higher levels of safety for their customers. Such databases contain patterns, mail server IPs and other info about spam messages recently detected by these organizations.