Users with administrative privileges are able to view members' account information, but are unable to view the members' settings in ArcGIS Online. 

Workaround

1. In ArcGIS Online, click the Organization tab.
2. On the Security tab, enable the 'Allow members to edit biographical information and who can see their profile.' setting. Enabling this option along with 'View all' (under role settings: Administrative Privilege > Members) gives users the ability to add emails to their profile bios.

Steps to Reproduce