a virus scanner isn't able to guess passwords and it is the sense of a password that the protected file is unreadable without it. It's the same with encryted e-mail. There are two ways to resolve the dilemma one is to scan e-mail on the desktop PC (it is recommended to have more than one virus scanner anyway) the second solution is to convince Astaro to add a 'block suspicious e-mail' button. Afaik Kaspersky marks unreadable attachement as suspicious - wouldn't be a big thing to block those e-mails.
we also have desktop virenscanners. Your secoond answer would be greatful !! Astaro should think about it. I only want to show these people that it is possible to pass by virus mails......