The ims-ms channel is a multithreaded channel, but does not respect the threaddepth channel keyword. Instead this channel uses a hard-coded value of 5 (maximum of 5 messages handled per thread). The ims-ms channel does have a channel option to control how many threads will be used within a process, DELIVER_THREADS. This option would be placed in msg-/imta/config/ims-ms_option The default value for this channel option is 15. (Note like other channels the channel option file is not present by default).