I am using Outlook for Mac 2011 version 14.4.3 on my MacBook Pro OS 10.9.4. When I receive emails from customers who use MS Windows, with attachments, many times the attachments show up as Winmail.dat files which I cannot open. Is there a setting or something that I need to do to be able to open and use these attachments? When I forward the emails to a PC Windows machine in my office, I can open the attachments with no problem.