subject line -- to hide or not to hide

[sen_ml@eccosys.com]

hi-

  i've been wondering whether there is a good way to keep the subject
of a message confidential w/o losing the convenience for the recipient
of having a meaningful subject line.

  my first thought was that i could just leave the subject line blank
(or make it bogus) and upon decryption of a message, a recipient could
figure out the subject themselves by reading the message...

  this seemed to work ok for a while, and then later, i wanted to
perform searches by eye as well as by subject.  this doesn't work very
well w/o meaningful subject lines.  it just doesn't mesh well w/
existing mail client interfaces.

  so, my question is, is there a good way to maintain the convenience of
meaningful subject lines and the confidentiality of them too?

  the thought of including a pseudo-subject header in the body of the
message that gets encrypted occurred to me, but w/o some kind of
client support for such a scheme, it doesn't seem very useful.

  is there something that already addresses this issue nicely?  anything
in an ietf draft or rfc somewhere?

  anyone else have this problem?