Nextcloud version : 11.0.1
Operating system and version : Debian Jessie
Apache or nginx version : nginx 1.10.3-1
PHP version : 7.0.15-1
The issue you are facing:
In the Admin Panel on the sharing Tab, i see all settings but the Setting:
“Allow user to send mail notification for shared files” is not visible.
Email config is set to php and works without problems.
Tried disabling the email sharing app and reenable it, but with no success.