As I know all members here are honest law-abiding citizens, I post this as a PSA.

Anything that contains advertising no matter how old, yes it's stupid, is not eligible for Media Mail. The Post Office can open your package to verify it qualifies.

Media Mail

Note the language, Upon such inspection, matter not eligible for the Media Mail rate may be assessed at the proper price and sent to the recipient postage due, or the sender may be contacted for additional postage."

Interesting point and important for sales of old magazines.

Also found it interesting that loose leaf educational material is allowed for medicine but not for any other educational purpose.

Thanks for the tip.