Great stats in this. I just learned of this today at the Digital Marketing World Event in one of the sessions (great event!). So, just in case you haven't had a chance to download it...
"Get the latest email metrics, trends and insights and see what is working in email marketing! We examined data from over 350 million emails in 21 different industries from the first six months of 2008. This free report is filled with charts, analysis and actionable steps that email marketers can take to improve their email campaign ROI.
How soon people open their email
What are the best days to send
What degree of personalization results in higher click rates
Whether smaller lists tend to outperform larger lists
And more... "