Most people understand that it's illegal to open mail that's not addressed to you. What's not so widely understood, is just how serious the consequences could be. Intentionally opening, intercepting or hiding someone else's mail is the felony crime of mail theft which comes with some heavyweight penalties, including five years' incarceration in a federal prison. You should be okay if you open mail accidentally, as long as you take the proper steps to reunite the mail with its owner.
It's a federal offense to open mail that doesn't belong to you. If you do it intentionally, you could be looking at a $250,000 fine and up to five years in a federal prison.
When You Intentionally Open Someone's Mail
Doing anything at all with someone else's mail could land you in serious hot water, even if you just glance at the return address while handing it to them. A couple of federal laws make it illegal to take, steal, intercept, open, damage or destroy someone else's mail, impede the delivery of mail, or pry into another person's secrets. If you're caught doing any of these things, you could be looking at charges of mail theft or "obstruction of correspondence." Both crimes come with fines up to $250,000 and five years in a federal prison.
When You Accidentally Open Someone's Mail
Obviously, the law is not going to punish you if you didn't know it was someone else's mail when you opened it. It's extremely easy to open a letter without paying attention to the addressee, especially if you're opening a big pile of mail and the letter was accidentally posted to the wrong address. It's what you do next that's important. Toss the mail in the garbage, and you're potentially obstructing the mail delivery, which is a federal crime. The best thing to do is re-seal the letter, write "Return to Sender" on the envelope and pop it back in the mail.
When You Have the Owner's Permission
When someone has asked you to open her mail, you're not going to get in trouble by following those instructions. The U.S. Postal Service is chiefly concerned with items that are deliberately stolen from a carrier or a mailbox because those items can be used to commit another crime, like identity theft. They're not going to care that you're opening a neighbor's mail while she's in hospital. If you have permission, then it's highly unlikely you're going to wind up court on federal mail theft charges.
When You're Managing a Deceased's Estate
It's not illegal to open someone's mail if the addressee died, and you are authorized to manage her estate. In this situation, you'll need to fill out a redirection request at the post office, and USPS will make sure that the deceased's mail is delivered to your own address. But, it's against the law to break into someone's mailbox even if you're legally permitted to read the mail – do this, and you could be charged with the crime of mailbox tampering. Redirecting the mail is the safest way to make sure you stay on the right side of the law.