Yahoo! Mail Classic automatically scans an attachment when you click the attachment name above the message, or, in the case of an image, when you click the thumbnail just below. If the file's clean, a green bar appears below the file name with the message "No virus threat detected". And, if your browser does not block new windows from opening, the dialog window to Save or Open the attachment opens automatically. If it doesn't open automatically, you can either click the Download File link or change your browser settings.