Mailing as First Class Package, using large envelope but not rigid?

[billythekid16]

I had been mailing magazines in 9x12 and 10x13 envelopes, not bubble mailers. To make it acceptable as a First Class Package, I always sandwich the magazine between two pieces of cardboard to make it rigid. But let's say I have a magazine (1/2 inch thick) or a paperback book (3/4 inch thick) that weighs 15 ounces, would it be okay to send it in a large envelope using FCP, even though it is not going to be rigid when you feel the envelope with the magazine or book in it? I had been wondering if "thicker is better" and that trumps "rigid" in this particular case.

[southern*sweet*tea]

Large envelope has a weight limit of 13 ounces, even at a commercial rate. I tried to print a large envelope for 14 ounces on stamps.com . It's not possible.

https://www.usps.com/ship/first-class-mail.htm

[gone_4_good]

You can send boxes as first class package up to 16oz

Just choose package and put that label on the envelope if its over 13oz or too thick/large

so yes I stuff all sorts of stuff into envelopes and ship them first class package - never a problem