Rewrite Zmodem using state machine and avoiding static variables

Write janus, hydra?

Support BSD terminal control

Check available space when receiving

Check if there is mail before calling

Option to generate a gatewayed "reply-to" with a fixed domain

Lock if[un]pack against simultaneous execution

Execute ifunpack when ifcico finishes receiving

Check Xmodem bug

in openfile(), check for the presence of the file in inbound

Change timeout checking in protocols

Move space checking to a separate module

Make system independant file locking (working over NFS)