Great comment, Samuel_Michon. One thing that is interesting to me is that your newsletter requires ppl to click through to read the entire article (as does Peter's newsletters). This probably also helps with the accuracy of open rates. Even if a reader doesn't display images, Mailchimp (as well as other email service providers) will know if he/she opened the email via the click. So, it may be a more accurate count over an email that doesn't have any links in it... (just some speculation)