Outlook Sceurity Delima

I have a group of people using one PC and want to set each of them up for internal EMail on an exchange server. I don’t want to have them log off the pc to change profiles each time. Is there any way to set up Outlook or Exchange server to prompt the user for a password to gain access to the individuals email within one windows profile. I remember doing it in the old Schedule+ for the schedule but can’t find it in outlook. Please Help.