You can take the MARTA train to the Dunwoody station. It is within walking distance from there.
There is a bus but I am not sure how close it will get you to the mall. You may have to walk a couple of blocks to the mall. You will have to get on line and go to either the Perimeters website or Marta's website for more information.
I'm sure but don't know the details. MARtA goes nearby too..
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