[imp] display addional icons on listview

[Aoi Klarmann]

Hi,

I want to display sort of 'validated' icon next to the message, e.g. the
column that contains the attachment-icon, if a message contains a header
value (think of server side parsing received headers to verify a message is
from a bank, or from amazon etc ) to limit successfull phishing attempts...

is that possible? how can i achieve that? in my case checking for a simple
header like 'x-org-passedtests' would be enough :)