Both mail services of EPFL and IPG use updated filters for checking spam messages and to prevent the diffusion of mail viruses. The spam checking is not a perfect science and user have to control if the filter is working correctly. To do this you can follow these instruction to interact with the IPG filter, or these instruction for the EPFL filter.

The Virus are always considered dangerous and suddenly blocked when they arrive to the mail servers. a message that contain a virus isn't delivered to users mailbox. NEVER. the users don't have control on what is a virus and not as happen with the spam messages. What is a virus is decided by the antivirus program, period.