Mailslots are an SMB-based IPC mechanism that dates back to Microsoft LanManager (LANMAN).
I could see using mailslots as a mechanism to disguise traffic and potentially thwart NIDS. SMB broadcast traffic is considered "noise" by a lot of admins and might well be excluded from traffic monitoring to prevent "chatty" traffic from filling the logs. Using mailslots, as opposed to rolling a custom broadcast-based protocol, makes the traffic sink into the normal SMB noise floor.
I could see using mailslots as a mechanism to disguise traffic and potentially thwart NIDS. SMB broadcast traffic is considered "noise" by a lot of admins and might well be excluded from traffic monitoring to prevent "chatty" traffic from filling the logs. Using mailslots, as opposed to rolling a custom broadcast-based protocol, makes the traffic sink into the normal SMB noise floor.