Cant view attachment except pdf

[testav]

I can't see any attachment in new window except pdf.Pls suggest

[6michel]

Hi testav 

Please, if you want someone to help you, be more precise in your questions.
Explain step by step what you have done, and the problem you are facing.

Yours sincerely. 

[testav]

For example I attach pdf file and ms word file with mail.when I opened the mail I can see both attachment PDF and DOC file.when I click on PDF file new window open where I can see the PDF file also there is option for download.But when I clicked on Doc file I can view this file in new window rather It directly prompted me for download.Why I cant view docs file in new window like PDF?Please suggest the solution so I can view DOCS file in new window.