Recently, I purchased something online and was presented with some different payment options. Apart from the normal choices (credit card, bank transfer, check) was "cash" — yes, cash. I puzzled about why anyone would prefer to mail cash, especially to another country. Then I read the note: paying by check or credit card involves extra fees that can be eliminated with a cash payment. "Make sure it's concealed securely; it would be wise to wrap the money in paper," the site suggested.

Well. Saving $10 or so sounded nice, and the postal service has had a pretty good track record of not screwing up, so I went for it. Or so I thought.

I strolled down to the local branch of the USPS to mail my not-yet-concealed cash payment, and promptly made the mistake of talking too much. I asked the friendly postal worker about the most secure way to send money overseas.

"You can't. It's a felony."

"What?" I asked.

"It is against the law to use the USPS to send money," he replied in a completely serious, don't mess with me, I work for the government tone of voice. Now why on earth would they make something as innocuous as this an offense? I was feeling a bit defiant at the moment, so I went for it.

"Why on earth would that be illegal?"

It was apparently a slow day at the ol' post office, since he didn't try to get rid of me right then. "You can't mail cash. Don't do it."

The more he didn't want to tell me, the more I wanted to know. "What is a law like that supposed to accomplish?" I prodded. Nothing, just another rehash of the same few sentences. He was a Talky Tina doll, and I was the little kid pulling at the string. I gave up and decided to have some lunch.

About an hour later, when I was pretty confident he wouldn't still be there, I came back. Sure enough, he was gone. I got in line and pretended to be extremely interested in the change of address form on the table. My turn came, and I looked the lady in the eye. She must have had about ten grandchildren. She'll have some common sense, I thought. "Hi, what's a good way to send money? I want to be sure it gets where it's going."

"You can't mail cash. It's a felony."

Are these people robots?! "Um... do you happen to know why?"

"That's how the law works. Sorry."

I gave up, went home, wrapped my cash in about seven sheets of notebook paper, stuffed it in an envelope, and went back to the post office to mail my harmless, completely legal letter, all the while contemplating all the people who send birthday cards with $5 or $10 stuffed in them, or the person with a pen pal in Spain who just wants to see an American dollar. These people are outlaws, and most of them don't even know.