[Exim] EXIM & PKI

Hello,
I was wondering if anybody is using PKI signed emails (or similar), does
EXIM handle these types of messages without altering them?
If so do I need to turn on S/MIME support?
Any help would be appreciated!
Thanks.
Warren

Warren Daly               HEAnet Ltd.
Network Engineer           Brooklawn House,
Tel:+353-1-660 9040          Crampton Avenue,
Fax:+353-1-660 3666       Shelbourne Rd,Dublin 4.
mailto:warren.daly@heanet.ie
Web: <http://www.heanet.ie>