International Mail Received With No Stamps, No Meter, And No Postage Paid Marking

Received an ebay lot of on paper stamps today from Republic of Ireland with nothing on the mailing to indicate postage was paid. The envelope's only markings are sender's and recipient's (my) information, plus a USPS bar code. These have been edited/ blurred on the images. There are three light purple bars on the back of the envelope, but these do not indicate that anything was glued, taped, or otherwise attached or removed.

Has anyone else here ever received anything like this before?

Not in 20 years....No
"Strange days indeed" Lennon.