- add top-level `hostname $(hostname)` directive (required by maddy 0.8)
- invoke as `maddy -config … run` (global flag before subcommand)
- fix dkim syntax: `dkim DOMAIN SELECTOR` (no key-size positional arg —
that was being parsed as a second selector, generating bogus keys)
- use bounce block on local_queue target instead of (local_routing) macro
