Is it lawful to look into a mailbox to verify an address?

Looking into a mailbox to verify an address is not lawful because it constitutes an invasion of privacy and is considered criminal trespass. Under federal law, mailboxes are deemed the property of the U.S. Postal Service, and the contents within them are protected from unauthorized inspection. This applies regardless of whether mail is present or if the mailbox is locked or unlocked. Accessing a mailbox or inspecting its contents without the owner's permission can lead to legal consequences. Therefore, it is essential to respect the privacy associated with mailboxes and to find alternative, lawful methods for verifying addresses.