Filtering a report via the Report Link

Hi,

I am trying to build a report that shows either Lead data or Contact data and relevant activities depending on if the person i'm interested in is a lead or a contact. I need to link to this report from within an email and am struggling with what to pass into the report URL

Here's what I've done so far:

- Created a combined analysis report using the Activities subject area

- I overlapped the ID fields for the contact and lead so regardless of which ID is provided the results will come back.

- I'm displaying it in a dashboard b/c I can't do a filter on a combined analysis without a dashboard.