I think it's possible using their APIs, which expose customer analytics data: get data for a campaign.
You could get data across all of your campaigns and run analysis across them. I think you could also export the data as a CSV and run it with some excel magic :]
Wow, thanks for sharing this. I love that human touch, both that it comes from a person and looks like plain text. Is that technically a transactional email, or is it something people can unsubscribe from? Seems like a bit of a grey area.
Lol. Definitely a fun one. Also, thanks for pointing out that this forum doesn't properly sanitize HTML :P
For those wondering, the hack is:
<!--[if gte mso 9]> Please get a better email client <![endif]-->