Here are some sample filters that provide some examples of Poco's filtering capabilities.

Note the use of the "Case sensitive search" checkbox.
icon beside each message but people can abuse that feature. Here's a way that you can turn off this flag when reading messages. The technique below demonstrates how to do this for messages from people whose addresses are not in one of your address books.
Note the use of the "and" operator to join the two conditions and the use of the "match only if not found" to screen for email addresses not in one of your address books. (The %addressbooks% syntax is an undocumented feature that checks the indicated header against your address books to see if the address exists in it). You can also use this technique if someone you know is in the habit of crying wolf too often. :)