Alerts for traps are sent out from Trap Viewer
1. Login (RDP) into your primary poller (Server2) , All Programs -> Solarwinds Orion -> Syslog and SNMP Traps -> Trap Viewer
2. Trap Viewer -> View -> Alerts/ Filter Rules (Navigate to View tab and click on Alerts/Filter Rules)
3. Set an alert the way you want by adding a new rule here (Alerts/Filter Rules is similar to your alert manager and is self explanatory )
Hope it helps
search for posts from my on how to do this -- you have to do it using a custom SQL alert.
WHERE nodeid IN (SELECT nodeid FROM traps WHERE traps.traptype like 'CERENT-454-MIB:%' AND Datediff(day, traps.datetime, Sysdatetime()) < 1 AND traps.Acknowledged=0 )