6 - arrives as signed(?) json POST at seppo.cgi/inbox, check block
7 - goes to app/var/spool/from/<hash base64>/2024-04-26T194817Z/0.s
8 - add unique to app/var/db/ids.cdb
9 and to app/var/cache/from/<hash base64>/2024-04-26T194817Z/0.s
10 and app/var/cache/from/<hash base64>/p-0.xml
14 - how do we stitch the replies? cdb? id -> reply-id
15 - how do we do replies to incoming?