I have a pet hate (I have more than one to be fair) of people quoting Open rates when it comes to email reporting. Open rates tell you nothing! They can have false positives as well as false negatives.
‘Opens’ are triggered when either the email’s images are downloaded, or a link is clicked within it. So, if an email is downloaded, but images are downloaded, it won’t count as an open – and if an email is read in Plain Text it won’t count either. Alternatively, if an email client automatically downloads images, it can count as an open even when it hasn’t been looked at.
Your click rate is a much more accurate portrayal of how the email has performed – as is unsubscribe rate and your actual conversions.
However, open rates do have a use. If you have an email that goes out regularly, like a newsletter, to a fairly consistent list, you can see the trend. Looking at any particular one-off send won’t tell you anything but seeing the rise and fall over time, will give you an indication if anything’s going dramatically right or wrong.