Hi Dan S.,
Assuming you have 2 Programs for that piece of content:
1. Content Channel tracking promotion on your site - Lead has downloaded and reached Success
2. Email Channel Program for use in the CEE - When a lead is marked in Program 1, also make them a member of this program, but not a "Success" status.
There are a number of ways to do this, but the fundamental issue is that the Program that the email is being sent from needs to have that lead as a member in order to skip it in your Stream. Just don't mark them as Success in that 2nd program so that your reporting is correct.