A System Administrator's duties and responsibilities encompass more than technical knowledge and power over their machines and data, a good sysadmin will never abuse rootly powers.
Yes, in troubleshooting email issues, an admin may have to get into another's mail queue, but they should treat any knowledge so gained as private as they would have their own mail. A sysadmin who succumbs to the temptation of reading others' files is a poor admin indeed.
Similarly, unnecessarily deleting files that are not their own or capriciously removing lusers' access is amusing to read about but should be anathema to a good admin.