- Seen-bys should prevent export to fido if node present. And maybe write 
  a utility to extract seen-bys from the $NEWSCTL/log? Or something like 
  that... Really creating correct seen-bys in outgoing echomail is important.

- ifpack and ifunpack should be written - ifunpack as a frontend for
  iftoss and ifpack to convert .out packets to arcmail fileattaches

- Support "flavours" - crash, hold in ifmail (maybe use free name, e.g.
  ifmail -r hold@f123.n456 ? Will pathatlias driver like it? Hmm...)

- Support several naming conventions runtime-selectable
