I'm not going to claim that this woman wasn't being a racist (she clearly was) but I don't think this was really about race at all ...
She was being a bully, and the goal was to use intimidation to get her way; and she has probably been very successful with this strategy in the past. There are two common responses for someone in the postal carrier's position, to give into the demands of the person instigating to remove conflict, or to retaliate. If the postal carrier caves the woman 'wins', if the postal carrier retaliates being that she is a "small defenceless woman" she will (most likely) get his boss to cave and the woman "wins".
Effectively, it isn't that different from a temper tantrum that the typical 4 year old will throw; and it should be dealt with in a similar way.
