First thing to check would be SNMP/WMI connectivity. Are you seeing current CPU/memory usage?
Looks like it just took some time. I had waited for a couple pooling cycles and I continued to check until about 4:40pm last night (about 30 minutes) but it appears to have corrected itself at 2:57am as the logs show "Hardware health monitoring on Dell 6248 Switch is up"
but to answer silverbacksays question, I had previously confirmed SMTP connectivity by testing the connection against my poller and listing resources. Unfortunately the device doesn't show any CPU information only Networking information like "Packet Loss", "Interface utilization" and Polling details.