A spam filter is a piece of software that is installed on a mail server and keeps track of all incoming emails to impede any unsolicited ones from reaching a certain inbox. A few instances of such emails would be: offers for pills or cash, fraudulent banking statements or attachments that contain malware sent with the idea of infecting your personal computer. Email filters typically check the content of an email message and if they detect given keywords or other dubious content, they either delete the email message or deliver it to the Spam/Junk folder instead of the Inbox folder. Some providers mix their own filters with up-to-date databases from spam-detecting organizations, so as to ensure better security for their customers. Such databases include patterns, mail server IP addresses and other information about spam email messages recently reported by these organizations.
