Power Supply column shows "Error" in the GUI for Symantec Messaging Gateway (SMG).
Also in messages log similar entries can be observed:
2015 Jun 17 09:10:12 (crit) SMS::Hardware: Power supply redundancy in Unknown state
Issue might occur on following appliance models:
SMG8380 (Dell PowerEdge R720)
SMG8360 (Dell PowerEdge R620)
SMG8390 (Dell PowerEdge R660)