Use the filters action to filter your email messages based on words that should be present in the From, To, Subject and Body fields. You can also filter your messages based on the submit date of the message.
To be able to filter messages based on words on the body of the email you need to check the option to "Parse the body words" at the email source:
When an email message has the defined words then it generates a TRUE condition. When some word is missing then it generates a FALSE condition.
You can place several actions under each True or False condition. The Filter Actions can be chained to create customized extraction jobs.