You know, its really hard to say I've had photo mailers come back to me priced at first class and not package rate just fine and I've sent out envelopes with photo mailers inside of them priced anywhere from 1.56 (1st class) to 1.90 (package) depending on the employee. Sometimes they try to flick the envelope when its on the scale to see if it bends sometimes they dont. In short I would price it out at package rate to be safe.

Hi,

I'm off to the US later this week and am taking a few things that I will be sending off. My SSAE's are cardboard backed and 10.5 x 8.5 inches. I have priced them up on the USPS website, but am unsure if they are:

"First-Class Mail® Large Envelope"
or
"First-Class Mail Package"

The package seems to be the same as the envelope except for the rigidity - can anyone confirm which category a cardboard backed envelope falls into?

Many thanks,
Bob.