We have noticed a general issue with the reliability of delayed messages using the x-delay message header and x-delayed-type exchange. Specifically, as the size of the mnesia database grows, delayed messages become gradually more and more delayed.  The delayed message plugin does not respect the delay times in any predictable way. We have some messages that delay 2000 milliseconds, some that delay 900000 milliseconds (15 minutes), and a variety in between. We are seeing messages come through the system as much as 3 days after being queued with an x-delay header of 900000 This behavior is similar both inside a 2-node production cluster, and in our test environment which consists of only a single node. We are able to work around the issue by deleting the mnesia tables, and allowing it to be recreated by the system.