Hello, there are a few settings that can explain why an email is tracked to the CRM.
1) the user personnalized settings, on tab "Email" under Select the email messages to track in Microsoft Dynamics 365 = Track should be set to "No email messages" if the user doesn't want to track every email from Outlook. And by the way it is not only CRM users that have tracked emails. Also the users that don't have licence could have tracked emails.
2) If an email originating from the CRM, let's say from a case, there could be a setting that automatically tracks responses from that email. Usually this type requires a reference in the object such as a number.
3) If the Outlook user used the Dynamics 365 complement to track the email, it shows a blue square with the mention "tracked to dynamics 365" in the category column in Outlook.
Cat
