Gmail did something like this back when it had ads. If it detected an email related to a death, it would attempt to block related ads from displaying above the content, so you didn't get pestered with ads for funeral services while receiving news of a loved one's death. From my understanding, it didn't always work, but was an interesting first step.

I don't know if other Google services now incorporate similar behavior.

(This is the earliest reference I can find to the behavior: http://staugustine.com/stories/060504/bus_2366168.shtml)