New SPAMsign: empty text/calendar MIME part

[Philip Prindeville]

This is interesting.  Never saw this before.  Just got SPAM with an empty 
calendar section:

----_7068696c69707040726564666973682d736f6c7574696f6e732e636f6d_
Content-type: text/calendar; charset=UTF-8
Content-Transfer-Encoding: base64


----_7068696c69707040726564666973682d736f6c7574696f6e732e636f6d_——