Can I send certified mail to a PO Box
If you want to send certified mail to a PO Box, you can! However, keep in mind that the process is slightly different than if you were to send certified mail to a physical address.
When sending certified mail to a physical address, the USPS is required to capture a signature from an authorized recipient. Since there is not a recipient available at a PO Box address, the carrier will leave a notice in the box, letting the recipient know they can pick the letter up from the front desk. There, the recipient will be required to sign for it.
Keep in mind, if you use LetterStream to send certified mail, we give you access to the signature file right in your account. So you don't ever have to worry about destroying or loosing your green card for that letter.