If you need to change the time-out value for reading from a mailslot, you can FUNCDEF and call SetMailslotInfo.

The first arg is the handle to the mailslot.

The second arg is the desired timeout in milliseconds. Pass a -1 to set to wait forever for records.

FUNCDEF("SetMailslotInfo", "32, void, 32u", "kernel32",,"O 0")
IF SetMailslotInfo(handle, -1) == "" THEN
   SAY "ERROR:" UNIXERROR(RXFUNCERRMSG())