iCal, attaching emails to Appointments and To Do items?

I'm using iCal v4.0.4 (1395.7), Mail v4.6 (1085) and MacOSX.6.8 Build 10K549.and I just know I'm going to look so stupid when I get the answer!

When I create either Appointments/Events or To Do items, there is a facility to attach files to the item - so far, so good.

I can't find, however, any way of attaching an email to an Appointment/Event or To Do item.

I have today booked a car hire and received an email from the company confirming the booking and which includes much useful inforemation - and I want to attach that email to the Appointment/Event reminding me, several weeks hence, to go and collect the car.

Can it be done and, if so, just how?

Thanks.

Message was edited by: iBozz to correct typos