acl morning_hours time M T W H F 9:00-12:30
acl evening_hours time M T W H F 14:00-20:00
acl mynet src 192.168.1.0/24

acl msnmime req_mime_type ^application/x-msn-messenger
acl msngw url_regex -i gateway.dll
acl msnnew url_regex dstdomain rad.msn.com
http_access deny msnmime morning_hours evening_hours mynet
http_access deny msngw morning_hours evening_hours mynet
http_access deny msnnew morning_hours evening_hours mynet