Hi @Noboru_Tanaka,
First of all, you can disable “Profiles” and the “System address book” globally by adding the following line to config.php:
'profile.enabled' => false,
…and running the following command:
occ config:app:set dav system_addressbook_exposed --value="no"
See also here: Nextcloud Documentation: System Address Book
However, even after doing this, users will still be able to find each other via the file-sharing dialog, where email addresses are also displayed.
If you want to prevent this as well, go to “Administration Preferences” → “Sharing” → “Sharing Privacy Preferences” and uncheck “Allow account name autocompletion in the sharing dialog…” However, this will completely prevent users from finding each other in the sharing dialog, making internal collaboration impractical.
Important Note!
None of these settings should be used to implement actual multi-tenancy, such as offering Nextcloud as a service to completely unrelated individuals or organizations. Nextcloud is not designed for this purpose, and even with the above settings, it may still be possible for users to access information about others under certain circumstances. If multi-tenancy is your goal, you should set up dedicated instances for each customer or organization.
As far as I know, Property scopes correspond to the same settings users can configure themselves on the “Personal Info” page, and If you click on the “scope” of the Email field there, it explicitly states that you cannot set the email property to “Private” and explains why.
Conclusion
If users need to collaborate on this instance, inform them that their email address will be visible to others. Users who do not agree can either:
- Use a dedicated email address for Nextcloud if they do not want to share their primary address.
- Remove their email address from their “personal settings,” which will prevent them from receiving notifications and password reset emails,
and possibly from using some collaboration features.
EDIT: I tested it in the meantime. If a user doesn’t provide an email in their personal settings, the user name is shown in the share dialog instead, and sharing still works.
If collaboration is not required, go to “Administration Preferences” → “Sharing” → “Sharing Privacy Preferences” to adjust visibility settings.
If multi-tenancy is needed, setting up dedicated instances per customer or organization is the way to go.
