Do this. Pickup any office document ( Word , Excel, Powerpoint ) which was sent across to you & have a look at the properties.
Bet you could be amazed with the details you find.
In some documents I received I found details of persons who originally wrote the document, over a period of time it was changed hands & the new author simply edited it & sent it across as his or her own work.
Cleanup the properties before sending the file across.
Office 2007 & 2010 have a built-in feature which can be found under
File>Info>Check for Issues > Inspect Document.
And oh ! This is not a new Feature.
For office 2003 / 2002 ( XP ), you have to download & use an add-on.