dont know if you sorted this yet, but you can get IMC to stop discarding unknown traps or traps from unmanaged devices
Go to Alarm tab
In Trap Management goto Filtering Trap
Edit the rule "Unknown Trap Filter"
Remove tick in the "Filter Unknown Traps (Will be discarded)" checkbox
If the device is unmanaged and is only discovered as ICMP not SNMP then you will also need to edit the "Unmanaged Devices Trap Filter" rule and untick box to discard traps from your icmp devices
..now if only I could get my spam email appliance to get discovered as an SNMP managed device I would be happy :( Whatever I try it is just discovered as ICMP