Some spam software -- either installed on your machine or running on the
mail server -- is doing this. It's not an Outlook feature.

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Sue Mosher, Outlook MVP
Author of
Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers
http://www.outlookcode.com/jumpstart.aspx
> most emails that I get, even ones that are responding to me, have the word
> [spam] in the subject line. how can i get rid of this?