RatelimitOutbound

To rate-limit outbound messages requires an assemblage of facilities. You will need to add a router:

• Early in the chain
• not active for verify
• limited to the items of interest
• redirect
• redirect supplied by an acl expansion, calling an ACL which
  • tests using a ratelimit ACL condition
  • returns either the original recipient, or :defer:

You will also need to be starting queue-runners at some reasonable frequency.