How should I mail a debt verification letter?

also...some of these addresses of the collection agency's are PO Boxes, not sure if that matters.

Doesn't matter when it comes to the USPS. The main thing is tracking numbers.

Registered mail is a letter that every time it is handled by a USPS worker, they sign a log. Certified is almost the same, except that it is only signed by the first USPS person that received it and the last person (route carrier). Return receipt is a card the receiver signs that is mailed to you.

If you want to learn more about the services of the USPS, go here:

http://www.usps.com/send/waystosendmail/extraservices/certifiedmailservice.htm

That is the certified mail page, but there are links at the bottom to the others. My opinion, you should at the least send it certified mail with a return receipt. For safety, spend the extra bucks and go registered mail.

It doesnt really matter if its P.O. box. The post office just leaves the card in the box letting them know they have a letter that needs to be signed for,just as if it was in a home mailbox.I have sent mine to p.o. boxes before, never a problem.

I always send mine via certified mail with return receipt. It costs $4.64 and it forces the addressee to sign for the letter you've sent them. You can have the return receipt sent to you by mail or e-mail. I've never had a problem sending a CL to a PO Box.

Always certified mail..........