test_email/test_email tests the compat32 policy.  test_defect_handling tests the default policy.  Thus they are not redundant, except of course that they are...it would be better to run the same test with both policies in turn, but I never got as far as setting up that infrastructure.

That said, for defects it may not matter, and for the other "redudant" tests sometimes the result is different, which is the point of the new policy.  So, things are in a bit of a limbo currently and could use some sorting out.  You'll note that in some cases in test_email I've noted where the corresponding test for the new policy is in the new test files.  There are a bunch more tests in test_email that need equivalents for the new policies (and I'm sure we'll find some bugs when that happens, unfortunately).