I find it amazing how the post offices differ in their 'regulations' .. I have no problems with bulging, wonky, heavy flat rate envelopes at my post office and believe you me, Ive send some doozies that were ready to pop at any given moment. And it still shipped!!!! All she said was 'if it fits, it ships!' I cant complain here all my stuff goes out.. However my postmaster, She recommends you ask for your local postmaster and bring it to their attention..