One of the great things about email as a marketing channel is that the results can be measured in almost real-time. Other more traditional channels such as TV and print don't give you this. You don't know if someone is sat in front of their TV watching your new advert or reading your advertisement in the paper. You can do research afterwards to try and judge the success of your campaign but there are no tangible figures.
The open rate statistic was introduced in the early days of email marketing and gave marketers a real time stat as to how many people had actually looked at their email. Unfortunately, over time people have become fixated with this statistic and ways to improve it, when the reality is this isn't a true measure of how successful your campaign is.
Clients often ask "what is the industry standard for an open rate?". My answer is why does it matter? The open rate is a vanity stat. You feel like your campaign has done well if you have a high open rate but it might not be related to the true success of your campaign.
We all know that the open stat isn't truly accurate to start with. If the email is previewed the image is loaded and an open counted even if the recipient doesn't actually read the email. Many email clients block images so no open is counted even if the recipient engages with the brand.
Let us assume that the open rate is accurate for your campaign. What does it actually tell you? It tells you the email was received by a certain number of people and a small image was downloaded. That's it.
What is the actual real objective of your email campaign? I'm pretty sure it won't be to get an 80% open rate and if it is, it shouldn't be. It is more likely to be to drive people to your website, get more people to visit your restaurant, buy your product in the shops or engage with your brand through social media. From here you need to work backwards and see how you can measure this success from your email campaign.
If you're driving traffic to your site then you can look at your click through rate and use Google analytics to see how much traffic was driven to your site from the campaign both directly and indirectly. Your campaign might have a high open rate but if your call to action is hidden away then your click through rate is likely to be low and hence the traffic driven to your site low. So a high open rate does not always lead to a successful campaign.
If you are trying to build brand awareness then you might look at how many new Twitter followers you get or Facebook likes to gauge your campaign success. The viral nature of social media means that this might be totally disconnected from the open rate for the campaign. A low open rate but yet a very successful campaign.
I'm not saying we should all completely ignore the open rate as it has its place as a metric. If you look at open rates over time you can see your open reach and identify trends for your campaigns. The key is not to use the open rate to judge the success of your campaigns and instead focus on the real objective of the campaign.