What path does e-mail follow within the above system?
This is probably one of the most complex questions to address because of the many originating locations for e-mail so I’ll address this in three parts; from the Internet, from the Sendmail server and from the Exchange server. If mail originates from the Internet, it is delivered to one of two load-balanced mail gateways where it is checked for infected attachments. If the message is infected, it is dropped. The gateway also has a list of known spammer domains and will drop the message if it originated from one of these domains. After it gets past all these checks, it is passed on to the Sendmail server where it is agains checked for viruses. The Sendmail does something special in that it will actually check compressed attachments for a virus. If one is detected, the entire message is dropped. The sendmail server also checks, through a logical analysis of the e-mail message, whether the message is spam. If the Sendmail server thinks the message is, the message gets marked as such in the
