Flat rate and Priority Mail boxes and envies look the same, with the exception of "Flat Rate" being on the ones that are limited prices.
I found out the same way you did...

I have not had a problem from California. But it has to say flat rate and there are different sizes in the boxes, which can cost a lttle more.

I have to argue with the postal employee all the time. Each one tells me a different rule. One day I had the luck of having two of the workers there at the same time and asked which one was right. They got into an argument! The head guy came out and said they were both wrong. Does any postal worker know the rules at all? It's frustrating when you ask and get different answers.

I tried to use the flat rate envelope like Marsye posted and I had to put tape all arpound it as I had it really stuffed and the PO refused to take it. Like Esqmommy said -you can only use the seal that somes with it. I had to take my package back home with me and use different packaging and it ended up being cheaper and I could tape it all I wanted!

Our PO has samples and the prices in a case...it's kinda hard for them to argue with anyone now LMBO

i've sent flat rate that weighed a ton but was still the same rate. if you can squeeze it into the envelope, it's that rate. there are two sizes, wee and okay. each has it's own rate anywhere in the usa.

As for the adhesive question, some of those envelopes do not seal, even if it has only 1 sheet of paper in it. If that is the case, you need to show the defect to the postal employee, try another envelope, and move on.

As for the rates, check out this website: http://pe.usps.com/cpim/ftp/manuals/.../Notice123.pdf

This is a booklet that the Post Office puts out that should answer ALL of the questions you have about cost to ship. We use it at our office all the time, and have several of them around, just to make sure that we don't get overcharged. Some government employees are not the brightest, and some just don't know where to check to make sure they are giving you the right info. I recommend you print yourself a current copy, and take it with you in case there are any questions.

And finally, there are also INTERNATIONAL flat-rate shipping containers, too. The small international box was something like $12.95 to mail in December '09 when I mailed to England. The box size? About the size of a VHS tape. Pricey, but easy. And my local PO worker didn't know there was a "flat rate international". The printed booklet helped.

Odessa

i tried to squeeze way too much in the big one and couldn't close it. my post office lade lade squooshed it and taped it for me. LOL!

I individually wrap all my boxes. I try to enclose a good book or some magazines with what ever I am sending and then request "book rate" at post ofc. It is usually 1/3 to 1/2 of what the priorty or flat rates packages are and even tho it takes a few days more for recipient to receive it, it saves me alot of money.

my post office told me they're discontinuing media rates. who knows? the right hand doesn't know what the left hand is doing.