Hello,
1) I don't know how experienced you are with DNN. - Do you know about the security roles that you can setup to give access to certain users. - You could set this up and then just give access to that particular user so that they can edit the info in a dnn module. - Is this what you mean?
2) If you import all of the users into your DNN installation you can use the built in Newsletter module to send an email to all of the registered users. - But, however, beware that I discovered that once the user list went beyond 500 users, the module failed to send all of the emails. - There is a module you can buy from DNN modules:
http://www.dnn-modules.com/Default....x?tabid=38which is more reliable than the Newsletter module, I have used the Email Manager module, but I haven't tested it on a large number of emails.
The current method I use for sending emails is to use a web service from
http://www.constantcontact.com" target="_blank">Constant Contact
as this is a much more reliable method and pretty much guarantees your emails will be delivered. I extract the registered users on the DNN site using a query in Enterprise Manager and transfer the results of the query into an excel file, I then upload the excel file to constant contact.
The downside to Constant Contact is that it is not a simple process that you can pass onto your client. - The easier method for your client will be to use the Email Manager module.
Hope this helps, thanks,