If a user is using outlook to connect to an exchange account and gets asked for credentials every time they log in, you may need to delete those credentials. Often times this is necessary if creating a new mail profile either doesn’t work or isn’t desirable due to other factors. To delete saved credentials, do the following:
Open User Accounts (on windows 7/8 just type ‘user accounts’ into the start menu and hit enter)
On the left hand side, select “Manage your Credentials”
There will be a list of windows credentials. Look for anything with ‘exchange’ in the name. Click the arrow to the right to expand the option, and then remove the credential(s).
Once done, restart Outlook and you should not be prompted for a password.