Issue
You want to see how many of your customers are viewing your emails in preview or without downloading images.
Solution
Marketo tracks email opens by embedding a single pixel image in tracked emails. When the image is downloaded, Marketo tracks the open activity, but people who do not download this image are still able to read and click on your emails. If you want to get an idea of how many people are doing this, the suggestion below can give you a general idea of the number
1. Create a smart list that checks:
- email was delivered
- email was opened
- a link in the email was clicked
2. Create another smart list that checks:
- email was delivered
- a link in the email was clicked
- email was not opened
By comparing the two lists, you will see which of your leads have blocked the images.
More accurate results about email activity can be found by creating an email performance report:
https://docs.marketo.com/display/public/DOCS/Email+Performance+Report
This report helps because, even if a lead did not "open" the email (download the image), if that lead clicked on a link in the email, it will also be counted as an open.
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