Encoding for internet email changes attachments extentions

[admin@osd]

I have a few users working under Outlook 98 that when the
send messages to certain internet email accounts, the
Lotus Notes server on the other end cannot interpret the
encoding on the message. Most cases the encoding is set
to unknown. I have tried to find where in their contacts
this settings is preserved but am unable to locate. Like
I said, this only happens with a handful of users and
therefore know it is a profile / user setting issue not a
company wide email issue. Any suggestions on how to find
out what the default is and where it is located would be a
great help.

Thanks,
Admin @ OSD