A Kensington resident is a liaison to the Brooklyn Postal Service and meets with them regularly. She has set up an e-mail account to receive complaints that she'll report to them. Please read more about this at Kensington Post Office (11218) and neighborhood mail delivery.
She has set up a new e-mail firstname.lastname@example.org solely to Post Office issues, which she will check regularly. She emphasizes that the more specific you can be about your service problems--dates, times, and places where the problems have occurred--the better able she will be to get help for you.
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