Responsible disclosure, anyone? I'm all for revealing the details of bugs so that we can learn from each other's mistakes, but at least give Apple a few weeks to patch the thing before blogging about it.
Also, I don't think the iPhone has the option to disable loading of remote content in HTML email at all (IT SHOULD), so no bug there.
At least this publicity might make people notice that Apples mail clients are setup by default to load remote content from html, whereas other clients are set to do the opposite.
I think I saw something like this a long time ago (pre-leopard).
I was running Little Snitch and while reading a specific email message, Little Snitch told me Mail.app was trying to connect using port 80. I denied it, but never tracked it down.
This is different than .mac addresses -- Mail.app will connect to .mac when you receive mail from someone with a .mac address (to verify if they're online, which you can disable I believe)
It is my understanding that this is a way for spammers to fish out legitimate email addresses. If the content is pulled from the server, the email address must be real.
At least, this is what I tell my clients when recommending turning off HTML content from untrusted email sources.
Correct. If I send a specially formatted email to an iPhone or Apple Mail user and they read it, completely transparently to them, I will be get "notification" of when they read it and what IP address they read it from. Even if they tell their client to not load remote images and to not honour read receipts.
And then they just put it in spam folder and what do you do with this information (They read it from this IP)? Sure, you know that email address is live and active, but what good is that info?
There's a million different uses. I could send an email to my friend and figure out if they're at home on their wifi or if they're out and using 3G. It's a general privacy issue.
Actually, they make the request to a unique URL which is tied to your email address and that particular "campaign", letting the sender know that you opened and read the email — and that you're probably a good person to send loads more spam to.
Regardless of how good spam filters are today, not opening the emails leaves you with less spam, and a lower chance of false positives/negatives in the long term.
Also, I don't think the iPhone has the option to disable loading of remote content in HTML email at all (IT SHOULD), so no bug there.