If you are on an Exchange network then you can use the Out Of Office
Assistant, if not then you can create a rule to reply. Here is a link to an
article with the steps to set up the auto reply, http://support.microsoft.com/default.aspx?scid=KB;EN-US;311107.
I hope this information is helpful.
Robert Findlay
Partner Technical Lead -- Outlook/Office Setup
Microsoft Technical Support for Platforms and Business Applications
