Sometimes as a PI you'll be asked to locate and or identify the physical address for the owner of a PO BOX or Postal Mail Box (PMB).
This can often be accomplished with a database search if you have access to credit headers. When people have a PO Box they will often use that address for their bills or car payments etc and the PO Box will appear on there credit headers as an alternate address.
If it's not there you may be able to contact the PO using a form available on the USPS web site. This form requires you to disclose the reason you need the information. The USPS will only reveal the information if you are attempting to serve legal service in proper person. They even require a case number.
Sometimes these methods will still fail. It could be that the owner of the box has relocated since they opened the box and no longer live at the address they provided the USPS.
You can try to pretext the PMB owner by mailing them professional looking material, free offers, maybe even a love letter, anything to trick the owner into revealing their identity. These mailings should always include a trap line phone number with call capture. If the mail box owner calls you'll get their information and can trace them that way.
This may sound like a lot of work for a simple PO BOX Break. Setting up trap lines , obtaining credit headers, printing up pretext post cards. Many investigators like to out source this type of work and purchase the information from an investigator that's already set up to routinely obtain this kind f information.
For assistance in performing a PO Box break contact Ed Opperman Pres of Operman Investigations Inc through his web site http://www.emailrevealer.com/