Cannot view file.

Hi
I have a user at work she use outlook 2010, she is not able to view fax file its .i3 format. The program I3 fax is installed she receive error “the file cannot be displayed because previewer software is not installed”, if she download and save the fax file which she received in email and then she is able to open it. Do you have any idea why she cant view it in outlook 2010? She use windows XP SP3.

Thanks