Post card question

I'm in the US.

Can I put ads on the left side of the post card below my return address?

Rick

dont put your return address there. split the back 1/2. On the right side of the back 1/2 put the address and barcode and put the return address in the same 1/2. You can use the left 1/2 for whatever. You can even get away with using a small portion of the 1/2 where the return and address goes depending. If it is classified as marketing mail, the PO will not return the card to you anyway. Depending on your call to action, you may not want a return address at all???? IMO