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Under some circumstances, it might be possible for Outlook's reading pane to tell senders that you've seen their mail.

If you have the "Reading Pane" in Outlook 2003 set to "ON", does that notify the sender that they have a legitimate E-mail address?


The reading pane can be part of the equation, but there's more.

You probably already realize that it's possible to embed images in HTML-formatted email. Images can be carried within the email itself, and that's relatively safe. But images can also be embedded in email as references, meaning that the image is not actually part of the email, but rather it's loaded from somewhere on the internet when you view the mail. The mere act of loading that image can be used by whomever sent you the email containing it to verify that you did in fact open the mail.

The Reading or Preview Pane is a particularly interesting because if your inbox is empty, it could automatically display the contents of the first message that arrives. Even if you're not there.

Regardless of how you display it, if the images are shown, then there's a possibility that the spam in your inbox can be telling the senders that the email address they just tried is real, ripe, and ready for more spam.

That's why in recent versions Outlook and Outlook Express default to not displaying images unless you explicitly say it's ok - either for a specific message or for senders you explicitly add to your "safe senders list".

Article C2242 - December 19, 2004 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

Not what you needed?

June 27, 2006 8:23 PM

I have a relevant Outlook Xpress 6.0 question. I get regular email notices from Wanted to, signed up for 'em. When the emails come, the images are not displayed by default. There's even a little message telling me that for security reasons, images are not display yaddayadda. That's OK with me, I don't care about that.
BUT...lately, I've been getting a bit of spam. Pornographic spam, from Japan or China or Korea or somewhere like that. The images -pornographic images- DO display. No choice, there they are in the preview pane for me and my children, pets, and wife to see.
First, I don't know how I got found (though I'm guessing it was through, since it seems they're forwarded from that site) and I don't want these at all, but WHY does OExpress 6.0 take such great pains to save me from pictures of things like USB drives in an email I explicitly joined, but drop the bombs on me with these spam emails from strangers on the other side of the planet?
Any ideas how to stop this behavior?

July 1, 2006 9:00 AM

The problem is that there are several ways to embed pictures in email. Images as attachments are shown in the preview pane, for example, or below the message. My suggestion, if it's a real problem, is to simply not use the preview pane. I realize that's less than optimal.

July 9, 2009 1:03 PM

While Microsoft may tell us all that the reading pane in Outlook is safe, please keep in mind that everyday, someone finds a hole in Microsoft's OS and other software to exploit. Just food for thought.

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