[imp] unqualified email address handling in HEAD..

[liamr@umich.edu]

Unqualified email handling seems to be a little off..  it generates address
like:

     username@@nameofwebserver.example.com

This happens when composing, forwarding, and bouncing.

Liam

sendmail error follows..
-----------------------------------------------------------------------

The original message was received at Thu, 6 Jun 2002 17:49:43 -0400 (EDT)
 from www@localhost

    ----- The following addresses had permanent fatal errors -----
 @
 @
     (expanded from: @)

    ----- Transcript of session follows -----
 550 @... User unknown
 550 @... User unknown