I've noticed that the EXIM mail program is setup with a filter (message_filter) to block email sent containing many file extensions, contained in the file /etc/antivirus.exim.
I am not concerned about the safetly of my users' computers - it's everyone's responsibility to run virus software on their local machine. My only concern is the server itself - if I enable some of these file types (.exe, .eml, etc) is there any danger to the server? Or just to the recipient, if he's stupid enough to open them?
