There is a limited ability to customize the display but this does not include either the ability to assign colours to the text of the subject nor the ability to change the style to your own preference. Below is a sample display of a portion of the poco index pane. You can, using a trick, assign a different background colour.

I used Poco's "message marking" feature to change the background colour of the "Format problem" and "FilterSearch script" messages s they stand out. This can be done from a custom filter that is very easy to build. The "Fwd: Press Release..." message is displayed in the standard manner (italics) for messages sent by the user.