delayed_queue_scan_interval — how often to call the maintainer for a domain
delayed_queue_scan_interval = 15
The primary function of the
delayed_queue_scan_interval option is to determine how often to call the maintainer for a domain; if there are messages on the active queue, then it is called at least every delayed_queue_scan_interval; if all the messages are on the delayed queue, then the maintainer is scheduled for when the next attempt on the first delayed message is.
Additionally, when the maintainer is called, it will sweep any delayed messages that are ready to go onto the active queue, so if there are constantly active messages then
delayed_queue_scan_interval controls how often delayed messages will get swept onto the active queue; this is how the option got its name, but it is not its most important function. This can be confusing because when the entire queue is delayed this option has no effect.
The default value for this option is
delayed_queue_scan_interval is valid in the global scope.