Final answer:
The user email address is the personal information that is NOT captured by default through Real User Monitoring (RUM). RUM collects data such as device model, operating system version, and browser type without intruding on personal identifiers like emails.
Step-by-step explanation:
The personal information that is NOT captured by default through Real User Monitoring (RUM) is c) User email address. RUM typically captures information such as device model, operating system version, and Browser type to help understand user interactions with a website or application. However, it does not collect personally identifiable information like user emails unless it is specifically configured to do so, as this would have privacy implications.