As far as we know, MailBluster uses Amazon SES along with Amazon SNS to track email events. When an open or click occurs, SNS sends the information to MailBluster, which then displays it. Essentially, AWS handles the tracking, while MailBluster stores and displays the data.
However, email open rates are never completely accurate, not just for AWS but for all providers. Opens are tracked by embedding a transparent image in the email and tracking the URL of this image. Most ESPs (Email Service Providers) don’t display images by default, which prevents open tracking. Gmail, however, uses an image proxy server to protect user information and sometimes opens the email before the actual recipient does, causing a false open event.
Therefore, accurately tracking open events is impossible. This explanation is based on our observations and experience. It might not be 100% accurate, as Gmail and other services do not disclose their algorithms. Nonetheless, this seems to be the most logical explanation based on what we’ve observed.