Java is a programming language and computing platform first released by Sun Microsystems in 1995. There are lots of applications and websites that will not work unless you have Java installed, and more are created every day.
IIS is able to impersonate the IUSR_<computername> account because the user name and password for this account are known by IIS. Before returning a page to the client, IIS checks NTFS file and directory permissions to see if the IUSR_<computername> account is allowed access to the file.
Indiana University uses enhanced email filtering services, which analyze all mail delivered to IU Exchange accounts. Any spam messages you receive are quarantined for five days in a Junk E-Mail (IU Exchange) folder in your account. After five days, the spam service deletes these messages automatically.