SP3: email notifications for Nstep workflow - Impossible to receive them. Are they correctly fired?

I am trying to receive some email notifications for my Nstep workflow page (a basic double page in my topnavbar on cropv2 on a fresh install of Jahia).

I setup correctly the root email + the super admin email + my users email. I am receiving without any problem the email for the std workflow. But I am not receiving anything for my Nstep workflow. The groups Users and Administrators are assigned on each step of my nstep workflow.

Is it normal? Do I need to reboot (and why?)? Are emails not sent for std Jahia groups and I need to manually assign some users?