When the Automatically accept incoming collaboration invitations setting is enabled in the Admin Console, the invitation mails to collaborate on folders may be sent to alternate notification email address, even though the Allow all users to receive Box notifications at an alternate notification email address setting has been deactivated.
This behavior depends on the notification type and processing. If you suspect that an invitation to collaborate on folder was sent to you, but you don't have any information about it on your primary email address, please check your alternate email address.
For more information about notifications settings, see Manage Notifications for Enterprise Users.