Hi Nagendran, There is no queue based processing for email listener rule. I believe this can be acheived at application level (instead of processing the email right then, queue first and process later). can you tell more about your use case?
We get attachment in the Email for each case , we will have to store those attachment in a external system for that we will make a service call to the external system. if the service call fails we need to retry it after some time.