[Exim] "callout ommitted when host testing"

Hi,

I'm just having a play with Exim 4 and its new callout facilities
and am testing with -bh, and wonder what the logic is for omitting
callouts when using that mechanism to test a configuration:

        Attempting full verification using callout
        ... callout omitted when host testing

I can of course get around this by exim -bd -oX but I'm just
interested why this is necessary.

Otherwise Exim 4 seems great and incredibly powerful. Congratulations
and thanks, Philip.

Ollie

--
Oliver Cook    Systems Administrator, ClaraNET
ollie@???               020 7903 3065