I am currently involved in a smaller-scale email campaign, promoing some new content we put up. I have received emails back within 1-2 days, if they were going to come.
However, I am very new at this still. You might chalk that response time up to the quality (or lack thereof) of my emails or the fact that this campaign hasn't lasted very long. If someone emails me back in two weeks, I'll be glad!
Hope that helps!
