If you don't open the email, and don't have the preview pane on, how would the image get downloaded either way? If you do open the email, and the spammer maps,

If you don't open the email, and don't have the preview pane on, how would the image get downloaded either way? If you do open the email, and the spammer maps, say, snotrockets@example.com to a unique AD-SRE21234.JPG filename and that image within the email is displayed, no matter if it goes through Apple's relay or not, wouldn't the spammer then be able to validate your address is both valid and actively opening spam mail at whatever time you opened it?