Need Help on this – Quite Urgent?

Hi I want to know if I can edit data present in Excel 2007 file, which is sent to me as an attachment in an email and is there in my Outlook (2007) mail box.

In case I edit the data in excel file (in the inbox) and forward it to others. Will the excel file, that is sent to others, include edited data or original data?

Also, if the excel file will include edited data – Is there a way through which the original data can be traced?

Another Question is: Is it possible to identify whether a particular Outlook 2007 e-mail communication, forwarded to me, is a genuine e-mail or not?

Any help from you guys can help me save my Career!

Thanks