For quite a while, there have been reports of workspace notification emails being dispatched despite a workspace being set for "no notifications." After the recent TYPO3 upgrade, the annoyance may have gotten bigger by notifying all members of a workspace instead of just the publishers (as happened before the upgrade).
After some tinkering with new settings in the upgraded version of TYPO3, I found a combination of workspace settings that effectively stops notifications from being sent. Workspaces that had "no notifications" set have been updated with these settings. In these workspaces, sending to publish or back to edit should not generate any notifications. You shouldn't even see the list of recipients in the now-really-no-notification "send to publish" and "back to edit" screens.
NDSU Admin has been updated with a read-only view of the workspace notification settings (since they're a lot more complicated than "on" or "off" after the recent upgrade). Hopefully some time this week or next, you'll be able to make notification setting changes using NDSU Admin, too.
Workspaces with notifications enabled can still uncheck recipients who do not need to be notified of a change each time a change is committed. Once NDSU Admin is updated to allow managers to make notification setting changes, managers in those workspaces will be able to set more fine-grained notification defaults for the workspace.
There are a few open bugs in the TYPO3 project related to workspace notifications, so we may have to be patient as bugfixes are released over the next months in case they change the way notifications behave (again).
Please report if your workspace is set for "No notifications" and workspace authors still receive email notifications.