I think that your numbers are a bit off, though. Going through the emails, there are several days where < 30 emails go to that list but there seem to be just as many days where it receives 75-150 emails. Some of these emails can be almost 500kB in plain text and I imagine that is what is causing problems.
There are a lot of problematic tests lately :/
In the last two-three weeks there seems to be 30-40 emails per in average.
I can disable NEEDS_INSPECTION as well and leave only ABORTED and CRASHED enabled. I'll do some estimate whether it helps substantially.
I blacklisted "depcheck: NEEDS_INSPECTION" results, because we don't intend to fix these problems any time soon (basically it means depcheck hasn't produced an output for some of the input builds) and they are very frequent.
That should help quite a bit.