Appriver is an e-mail filtering service used for faculty and staff e-mail accounts to prevent many viruses or spam e-mails from being sent to your e-mail inbox. If you ever wish to see a list of the messages Appriver has blocked, you may visit http://my6.appriver.com/
If you have not used this web service before, be sure to click on the "Register for Access" link on the right. Follow the instructions there to create an account for the service.