Read receipts are interesting. I was always annoyed with how the recipient of my email had to click 'ok' before I knew what happened. I wanted something that could work in the background. As I couldn't find a suitable solution out there I decided to build it myself!
If you want go ahead and check out ContactMonkey (
www.contactmonkey.com). Email tracking for Outlook & Gmail. We offer a free version too.
There are a few other solutions out there too. So don't just rely on my opinion!
Let me know what you think.
Scott