[rabbitmq-discuss] Schedule Messages

[Doug Barth]

We needed similar functionality. The way we implemented it was to
create a service queue that takes a message and headers to indicate
the target queue and when to deliver it. Messages are either delivered
immediately because their delivery window has past, or they are queued
to a beanstalk server with a delay. The beanstalk server will send the
message back to our process after the delay time is up, which then
delivers the queue to its target queue.