Hello @stpaulsoakland ,
Certain functions on the receiving end can affect open reporting.
If the receiving email program or domain runs any security and privacy elements that "open" and "click" in emails to check for malware, this can affect that reporting. This is something that all ESPs' reporting and tracking tools are affected by nowadays. Setting up self-authentication for your account, if you have your own domain, can help this with some email programs, as they'll default to trusting your emails more. However, some programs and networks will simply ignore this and perform their open and click functionalities anyways.
Since opens are tracked based on the 1x1 pxel transparent image we include with each, email programs that don't allow images to display until prompted will end up not giving us this report data. Outlook programs are especially particular about being prompted to show images each time an email is opened.
If you have further questions on these elements, please see the following articles:
Apple Mail's privacy policies and how they can affect you
Email open rates
Email click rates
... View more
