For a while Prof. x was getting a certain dietary supplement from one of those mail-order companies. He eventually decided to stop using it and canceled the standing order. The company was pretty good about it, but earlier this month sent another bottle of the supplement (Prof. x never opened the package: I called the company to ask about it and they said it was sent as a free trial because they'd reformulated the supplement). I put "RETURN TO SENDER" in red letters on the label, took the box over to the post office and handed it to a clerk. Yesterday, Prof. x got it back. This time I crossed out Prof. x's name as best I could with a Magic Marker, added "REFUSED 2x" for good measure, and intend to explicitly tell the PO guy that it's refused. Will this work? Am I doing the right thing?

It may or may not work. Since it is a "free trial," personally I wouldn't waste my time or the post office's, I'd just discard the product and write a letter to the company (possibly even sending it registered or with a delivery confirmation, and of course keeping a copy of the letter) stating that you attempted to return the product twice and that you will not waste your time doing so again. Request in the letter that no further product of any kind be sent, and that if any further deliveries are received they will also be discarded.

When someone sends you a product you do not want, and haven't requested you're usually under no obligation to return it (you can use it or discard it), and certainly aren't under any obligation to return it multiple times. I'm sure there's even a legal way to MAKE them stop, but that might mean involving an attorney.

The reason I'd send the letter (with proof I had sent it) is because then the company cannot say that you ordered the product and just are refusing to pay for it.

I agree with kaplods. I work at a credit union and have seen a lot of members get screwed over by these types of companies. They just keep sending you their product and automatically charging your card. Be careful of this and make sure to check your credit card statements too. If you see any charges you should call them, and document exactly what happens. If it isn't resolved right away, you can do a dispute with your credit card company and might even want to report the card lost and get a new one just in case. In most cases you only have 30-60 days to dispute an item.
I can't tell you how many times I've seen this happen.

I work at the post office and what you need to do next time is cross out the bar code at the bottom of the package if there is one. The machines sort the mail and put that code at the bottom so they know where to send it, that is why you got it back, and your carrier wasn't paying attention. If it says "pre sort standard" anywhere where the postage is that is third class mail and they don't pay to have that mail forwarded or returned so it gets tossed out. Anything with "first class" "Priority" "parcel Post" ect... will be returned to sender. Presort standard is just junk mail.

Thanks all. I crossed out the address but not the bar code. Maybe if it comes back yet again I'll tell Prof. x to just toss it (only problem is he doesn't like to toss much)

I had a problem like that with this company sending me stuff all the time- charging my card- me calling getting the money back, and so on.

Finally I called my cc company and asked the numbers to be changed- one more item came that I returned again- and I guess after they figured out my card didn't work anymore they stopped sending stuff HAHA.