Rewrite Zmodem using state machine and avoiding static variables

Write janus, hydra?

Support BSD terminal control

Make system status files (last call, retries etc)

Check available space when receiving

Check if there is mail before calling

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

Send some responce if requested file [not] found

Create different ^aMSGID-s for crossposted messages

Lock if[un]pack against simultaneous execution

Search attach files in protinbound and listinbound

Check if 1213/0 addresses are parsed OK
