Email tracking is a process that requires an installed extension to listen for email activity. For example, when you hit "Send" on your newly drafted email, Gmail or Outlook check to see if there are any attached extensions that want to do something with that email. If there are, they pause sending the email, let the extension do its magic, and once it says "good to go," the email is sent.
What happens in this process is that all links in the email are replaced with traceable links and a small image (pixel) is placed in the email body. As soon as an email is opened, the recipient loads this image, which triggers the email-open statistic.
Unfortunately, third-party solutions such as Apple Mail, Spark or other email software tools do not have this event built into their systems, nor do they offer ways to make the aforementioned extensions work on their systems.
Even with full inbox access directly with the Outlook or Gmail system, we cannot install this pixel image, nor can links in your email be replaced once the email is sent to your prospects. This activity needs to happen before the email is sent.