[Users] How to colour incoming messages?

[Adam Nielsen]

> > Is there a way to make sure the folder/preprocessing rules are
> > applied to newly arriving mail too, without having to leave the
> > folder?
> 
> Right-click the folder and use the 'Run processing rules' menu item.

This menu item is greyed-out for me.  Perhaps it only runs
the folder-specific rules (of which I have none) and not the global
preprocessing rules?

Cheers,
Adam.