Does this help?
http://support.microsoft.com/?kbid=312351
OLEXP: Message Appears Blank and Has an ATT000XX.txt or ATT000XX.htm
Attachment
Hal

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Hal Hostetler, CPBE -- hhh@kvoa.com
Senior Engineer/MIS -- MS MVP-S/U -- WA7BGX
http://www.kvoa.com -- "When News breaks, we fix it!"
KVOA Television, Tucson, AZ. NBC Channel 4
Still Cadillacin' - www.badnewsbluesband.com
> A friend of mine gets the subject attachment as an icon on the bottom
> left of every received and sent e-mail. She uses Win98 with OE, the 70
[quoted text clipped - 4 lines]
>
> What is this and how do I tell her to get rid of it, please.
Is she also seeing the message body OK?
If so, she likely has set Tools, Options, Read, Read All Messages in Plain Text. With
that setting, any HTML format message displays the HTML version of the message as the
attachment.
She sees the incoming message that way because the sender used HTML format. If she sees
it on only some of her replies, then she also has Tools, Options, Send, Reply to messages
using the format in which they were sent. She can turn that off.
So what see is seeing is by design.
If she does Not see the message body, then the article in Hal's reply likely applies.

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Mike - http://pages.prodigy.net/michael_santovec/techhelp.htm
>A friend of mine gets the subject attachment as an icon on the bottom
> left of every received and sent e-mail. She uses Win98 with OE, the 70
[quoted text clipped - 4 lines]
>
> What is this and how do I tell her to get rid of it, please.