Hello, I have Nextcloud 10 on my Ubuntu 16.04 and I have a problem with email app. My settings is configured five, I received test email immediately, but when I share files with other users, they don’t receive any email.
Could anyone help? Thanks 
Just to clear things up. The mail app is just a mail interface that directly connects to the mailserver the user configured. For notification mail, it is the admin who must set the settings on the admin-page (there you can also send a test mail).