dma user config

[Matthew Dillon]

     Generally speaking you do not want to have per-user DMA configs at 
     all, it's just too big of a security risk.

     What you could do is allow user extensions ala postfix style '.'
     extensions to the target name.  For example:

     dillon at backplane.com
     dillon.fubar at backplane.com  <--- also routes to dillon

     The per-user aliases file (~/.forward) can pipe to programs, which
     means it really has to be run in the context of the user.  DMA itself
     does not have to run as root but you will need a local delivery
     agent that either runs as root or is suid root.

						-Matt