On the right of the Profile Settings page, you can set email notifications per initiative. Click on an initiative to change those settings.
Planbox gives you granular control over types of emails you want to receive. You can even receive an email when a task is assigned to you. Edit your profile and you can configure notifications for each of the initiatives you are a member of. Please note that any action you are taking on yourself like completing your own tasks or commenting on them will not send you an email.