The iCalendar specification (RFC 2445) requires that
iCalendar objects sent via MIME must include a method
parameter in the Content-Type header which mirrors the
method in the iCalendar object.  For example:

Content-Type: text/calendar; method="REQUEST";
charset="UTF-8"

Using Python's email package, it is impossible to
generate a MIMEText which has that method=REQUEST
parameter because the constructor does not allow for
arbitrary parameters, only the subtype and the charset.

Logged In: YES 
user_id=12800

While the MIMEText constructor doesn't take a list of
parameters, you can easily add this after the fact by using
the set_param() method, e.g.:

m = MIMEText('foo', 'calendar', 'utf-8')
m.set_param('method', 'REQUEST')

or you can use the MIMEBase class instead of MIMEText.