When I took my F8th to the PO the lady said the way I had my fabric folded left a hump or ridge you could feel on the outside of the envelope. She said it would not go through their machines and would have to be handled by hand so it would cost more. If I refolded the fabric so it was the size of the envelope and left no ridges then it is cheaper. I took all my envelopes home, tore them open and started over. I could see it made a big difference. I really appreciate her help.
I learn something new everyday. If anyone didn't have enough postage added please let me know.