I want to implement dms in openerp 7.0. I read many documentation about dms. Created a database with dms & supporting modules.

But i cant send attachment mails, it shows error "AttributeError: 'NoneType' object has no attribute 'exists'" What was the error?

Any simple documentation of dms available with following features?

Features:

How to differentiate incoming & outgoing documents?

Priority & confidentiality level of each document?

Document Status?

User can accept & reject these document?