Registered/Certified Letters -- Why They Are Good
Dwayne, The U.S.P.S. protects you by your sending a letter registered or certified, because you then have proof, legal proof, that you sent a cease and desist (or any other type) of letter to someone who may try to come back at you legally.
These kinds of letters MUST be signed for by someone, proving they were received. You then receive a copy of the signature, date and time the letter was received, which you should then save for furture (hopefully unnecessary) use.
Any employee at your local Post Office will be both happy and able to help you determine if you should send your letter registered or certified (there are nuanced differences that I don't have memorized). And you, and all other Capri authors who are trying to ensure they get their own property back, should send your letters registered/certified, even if you've already sent one via regular mail and have had Capri confirm she's returning things to you. (For those sending a second letter, or confirming email and/or phone conversations, just start it with something like, "Per our initial conversation dated XX-XX-XX through XX-XX-XX, I am confirming again that...")
In situations like this, you want the law on your side. This is a cheap and easy way to ensure that you have proof that will stand up in court. Oh, and always keep a copy of what you sent in that registered/certified envelope.
P.S. Send via the United States Post Office, NOT via FedEx or UPS or any of the other overnight or ground carriers. It will be both cheaper and more legally sound.