Probably because of a misconfigured rule. For details see;
http://www.howto-outlook.com/faq/duplicates.htm
--
Robert Sparnaaij [MVP-Outlook]
Coauthor, Configuring Microsoft Outlook 2003
http://www.howto-outlook.com/
Outlook FAQ, HowTo, Downloads, Add-Ins and more
http://www.msoutlook.info/
Real World Questions, Real World Answers
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"SB" <SB DeleteThis @discussions.microsoft.com> wrote in message
news:249508D6-D6A8-4139-9D1E-39978398883C@microsoft.com...
> Why might I be receiving multiple copies of emails from some contacts, and
> not others?