Opening .dat Files On A Mac
I ran into this problem once when I received an email from someone who wanted me to read a pdf he/she had attached. It might have been from a windows user, but I did not have time to ask and simply needed to read the darn thing. I expected a pdf file and instead got a file that had the .dat extension. Imagine the frown on my face. I quickly did a little research on such formats in relation with macs and came across a nice site that carried the solution to my problem:
http://www.joshjacob.com/macdev/tnef/
It is free and easy to setup, and you will be able to extract the pdf/s from the .dat file with ease. Hope this helps.