File formats in Outlook-MIME format

I use Outlook 2K at work and home and sometimes I have received attachements as MIME formats. This seems to happen consistently when an AOL user sends an attachment to Outlook and occasionally with a ccMail user. It doesn’t seem to matter what the file was i.e. Word, Excel, a jpg, bmp, tiff or even a text file. They all show up as MIME files. I have never been able to access this file no matter what I try. Can this be avoided? More importantly how can I access MIME format files?