The latest malicious programs, undetected by all heuristic mechanisms, reach the virus monitoring laboratory, and thus their victims, only after criminals have begun spreading them.
It is imperative to take into account the probability of criminals being able to bypass a company’s security systems and access its network (or employees’ PCs) and also the possibility of criminals being able to impact the protection systems in use, with the goal of stopping their operation.
To minimize risks to mail servers in particular, user mailboxes should be scanned regularly with an anti-virus to check for the presence of previously unknown malicious programs.