What version of Outlook are you using and what version is the recipient
using? Also, does the text file look like an iCal appointment? Meaning does
it start like this:
BEGIN:VCALENDAR
PRODID:-//Microsoft Corporation//Outlook 11.0 MIMEDIR//EN
VERSION:2.0
METHODUBLISH
BEGIN:VEVENT
ORGANIZER:MAILTO:[email protected]
DTSTART:20050801T200000Z
DTEND:20050801T210000Z
TRANSP:OPAQUE