Apple has posted an AppleCare Knowledge Base document discussing how rendering an HTML email message might lead to more spam. It explains why you should have your email program configured to deny network access when displaying HTML messages.
To change these preferences in Microsoft’s Entourage or Outlook Express for the Mac, choose Edit >> Preferences >> Mail & News, then select the Read tab so you see the screen below. (Sorry, no examples for other programs/platforms at this time, but the procedure should be reasonably similar).
The most important option to leave turned off is the “Allow network access when displaying complex HTML.” Keeping this option unchecked prevents the techniques used to gather valid email addresses (yours!).
I always keep HTML rendering turned off, as well. Relevant information is still easily found when the HTML email is from a trusted source (Amazon or Ofoto, for example). And you can always turn rendering (and only rendering, not network access) back on temporarily to read a message that’s unintelligible.
Continue reading to see examples of messages with the “Display complex HTML in messages” option turned on and off.
This first image shows a message from Amazon with HTML rendering disabled. Amazon does a great job ensuring that their messages are easily viewed regardless of whether HTML rendering is enabled or disabled.
This image shows the same email message with HTML rendering enabled. However, the “allow network access” option is still left disabled, which is why the images don’t load.
Examples like these show why HTML email is overrated. Most of what you’re missing by leaving HTML rendering disabled is unnecessary design or marketing.