>SL4NT is not really touching the RAM usage. Less than 1GB of RAM is being consumed by SL4NT and there is nothing else running in addition on the server so plenty of RAM (>50GB) is available.
please note that SL4NT is a 32-bit executable and one GB of heap space is all such an application can get!
There can be no doubt that SL4NT queues received messages in RAM till all available RAM (1 GB) is used up.
Let's check out which action queues are responsible (if any):
Create under the registry key HKLM\SYSTEM\CurrentControlSet\Services\SL4NT\Parameters the following registry values of type REG_DWORD:
and set each of them to a value of 10000.
Start the service afterwards.
If now such an action queue fills up, some percent of it is purged and an a warning event log entry is written.
It's also possible that the receiver queue (which can not be limited) grows too large, but in this case the rate of messages received per second is just too high (do you have any performance numbers of incoming network traffic?)