Customer Portal User Groups

Customer Portal User Groups

I have been told by a customer that in the next couple months they wish to move away from generic accounts per dept into user based accounts. This means that every user will have an account so I'm looking at at least 1500+ users, at first i figured i could use the customer portal of the application but because this doesn't support group creation like the normal global user setup it'll make user management a nightmare.

the second option would be to have each user signup for a free account but because they are considered our customers having Zoho spam all their email addresses with the welcome, Hi my name is ____, and the your free account is about to expire emails would be less than ideal and unprofessional.

TL:DR: is there a way to create groups in the customer portal and assign permissions to only certain sections of the application based on the group membership or is there a way to prevent welcome emails from going to new users when they sign up for a free account?