After v4.2.7 upgrade, the “Recommended update email” was ON by default system wide. I noticed this afterwards, and then unchecked the “Send by default” box (under Conflucence Admin| Recommended update email | Send by Default ) . However, this seems only affect newer users. All existing users had, by default, already subscribe to it (from the top menu bar | User Name | Settings | Email | Subscribe to recommended updates is CHECKED).
It is important to allow users opt-in, rather than sending the messages by default. By the way, in our case, almost ALL newly created pages/comments made it to "Recommended ..." and therefore being sent system wide to ALL users within the permission setting. It is way too much. We have to stop it.
Can we update this setting on all users in the SQL database? In which table/field is this subscription stored?