Please see the discussion here:
http://outpostfirewall.com/forum/showthread.php?t=13477
This is what the feature is about:
Kai445 wrote:
"Sometimes my blocklists filter ranges of sites I
intend to visit (everything from paypal to sirius.com
to weird random sites).
Anyway, PG has a "Block HTTP" thing you can unselect so
the filtering still works for p2p apps but ignores
browser requests."
Csimbi wrote:
"I think this was requested a few threads below.
I think the reason why they said no in the first place
is performance - it would slow down things to check the
port numbers as well.
I don't think so - first check the port number, if 80
8080 etc: allow, otherwise check IP normally and block
if necessary. Just the port number check should not be
such a big issue - but it would be nice if it could be
customizable (the port numbers themselves)."