An email filter is a software app that’s installed on a POP3/IMAP email server and monitors all incoming emails to stop any unwelcome ones from reaching a particular mailbox. Several instances of such emails would be: offers for pills or cash, false banking statements or email attachments that contain malware sent with the intention to damage your personal computer. Spam filters usually ‘scan’ the content of an email and in case they spot certain keywords or other dubious content, they either erase the message or redirect it to the Junk/Spam folder instead of the Inbox folder. Certain web hosting providers mix their own spam filters with up-to-date databases from spam-tracking organizations, so as to guarantee higher levels of safety for their clients. Such databases contain patterns, mail server IPs and other info about spam emails recently detected by these organizations.