question regarding shipping through priority mail express

[StudioKatClayworks]

I was told (by a family member, not a postal worker, the office is closed or I would have called them to ask) express mail must be shipped in boxes like priority mail flat rate boxes

while I know there is express mail flat rate boxes, I thought regular express mail could be shipped with any normal package, like how regular priority mail (non flat rate) labels can be used on any package

which is correct?

thanks for taking the time to answer, today has been a really hectic day for me ):

[GrammaticalArt]

You can ship USPS Express in your own packaging. Just make sure you enter the measurements when you buy the postage. :)

[Former_Member]

You can ship Express packages in your own packages or in the USPS Express boxes.

The same goes for Priority Mail.

The only exception is when you are purchasing flat rate postage. Then the USPS Flat rate packaging must be used.

[ConcertinaPress]

I've shipped express mail in my own packaging! In fact, sometimes it's cheaper than if I used their flat rate boxes (like if my stuff is too small for the flat rate box, but too big for the flat rate envelope) - also, buying express mail postage online is MUCH cheaper than buying it at the post office, so make sure to print your label online.

[GrammaticalArt]

Yes! These two ladies added great additional info. :)

[StudioKatClayworks]

thanks for replaying everyone! It saved me so much hassle! :)

I used my regular bubble mailer, printed the label here and was able to drop it off in the express slow on the way to work! so glad I didn't have to find the extra time to pack it there :)

[OneFairfaxRoad]

It's often cheaper to use your own packaging for priority mail, particularly if the package isn't traveling cross country or is fairly light. Love that $100 insurance is included too!

[StuckOnSilver]

I think USPS Priority Mail only insures up to $50.