Quick tip, if you have iOS3/iOS4 on your iPhone/iPod Touch/iPad, you can disable loading remote images in emails by going into Settings > Mail, Contacts, Calendars, and flipping the “Load Remote Images” option to Off. By default, it is set to On.

Why would you want to do this since Apple has deemed it good to enable it by default? Well spammers can embed tracking in the image URL’s. When Mail loads the images, the spammers will know that the email address they sent to is valid, which of course leads to more spam. That’s why on the desktop Mail.app and Outlook by default have this disabled. Why Apple choose to enable this by default on the iDevice is strange.