Updateable CRM solution

Is there a CRM solution that allows customers to update their own details?

[Receptional]

I want our clients to ONLY receive stuff on the information they ask for - AND choose between recieving it by Email or by post AND I want them to be able to update or opt-out online (updated automatically on the database) every time they recieve a notification, newsletter or email. This last bit is the problem... are there any CRM solutions that fit this bill?

[backus]

I've sent you a stickymail. I don't want to make any program recommendations here.