Exchange2000-Missing Attachments

Attachments are intermittently missing from mail sent from one OUtlook user to another. Exchange 2000 and OUtlook2002 is installed on most clients. Also even if “Plain Text” or “HTML” format is selected in the OUtlook, then also “winmail.dat” file is included in the mail sent between 2 outlook clients within one domain and the problem still occurrs after selecting plain text. Problem is very intermittent.