I would just wrap some lightweight cardboard around it.

 

Fascinating question. I've honestly never even thought about something like this messing up a postal machine.
If I were you, I'd mail it in a padded envelope just so the key doesn't get lost if it pokes a hole in a regular envelope in transit.

 

I would think it would be fine. When we buy our county dog tags, they are sent to us in the mail, in a regular evelope. They are taped with scotch tape to a piece of paper inside. If dog tags make it alright, I don't see how a key would be much thicker/heavier.

 

tape it to a business card
Stick in envelope

 

Think netflix. That amount of stiffness is handled ok. Be aware that a padded envelope will require extra postage, simply because it is not machine friendly. I like the tape to business card idea.

FWIW, you actually CAN send a DVD or CD through the mail for the cost of a single first class stamp. The dimensions and weight just fit if you don't add anything else to a homemade cardstock (think file folder) envelope.

 

Tape it inside a greeting card.

 

customers would send me keys often. They just taped it to the inside the envelope so it wouldn't flop around in there.

 

Mail goes through those machines at a very high speed. It will jam the machine, causing damage to the rollers, and tear up other mail in the process. The key would most likely be torn from the envelope and lost in with the other torn mail. It would be best to put it in a padded envelope. Then it would be handled differently than the regular envelopes.

 

It would be better to get a padded envelope. I used to work the "re-wrap" desk at the Post Office. Sooooooo many things came apart from their "envelopes" (one was a class ring from the U.S. Naval Academy in Annapolis) and it was very sad we weren't always able to match up an item with an address. Can you imagine some nut so trifling he just stuck his class ring in a regular paper envelope? For gosh sakes! You can't be too careful in mailing things -- you should always get a bubble envelope or a box.

 

Put it between the pages of a thin paperback book and mail it media rate in a small manila envelope.

 

Unless I am mistaken you can only use "media mail" to mail "media' books, CDS and videos. Most of the time there is not that much difference between media mail and first class charges.

 

Cut a piece of light weight shirt board the size of the envelop. Tape the key securely in the center of the shirt board.

 

If you take the envelope to the post office you can request them to "hand stamp" it. If you're not taking it to the post office, as others suggested, tape it between two pieces of lightweight cardboard.