This is a severe limitation which stems from an optimization. I agree with the rationale, but we should at least have a plan for lifting this restriction in the future. One possibility would be to add another kind of Channel which uses event-sourcing instead of relying on message deletion, so that it could keep track of its own sequence numbers. While doing so, it could also ensure that the sequence numbers are contiguous per destination. It would be more expensive, but you also get something for it.