Mail thefts at holiday time are a serious problem. From one of our security companies and the USPS Postal Inspectors we have description of the crimes and advice:

Install a locking mail box on your property.  Ensure the type mail box you choose is solid and the top cannot be easily removed so the mail is accessible.
Collect your mail from your mailbox everyday as soon as possible after delivery.  Do not allow mail to accumulate even in a locked mail box.
Deposit out going mail into the blue USPS collection boxes before the final pick up on the same day of the deposit.  Check pick up schedules posted on the box to ensure your mail will not sit in the box overnight or over the weekend.
When expecting packages monitor tracking at or company websites so you know when to expect shipment/delivery.  A new USPS service feature provides email and/or text alerts to notify customers of package delivery.  Sign up at
Arrange with the delivery company to have it only dropped at your home if someone is there to sign.  If no one is there, have them take the package to Customer Service and alert you it is there for pick up.
Select an alternate address to have the package delivered.  This can be your business or a neighbor who is always home.
Security companies can be asked to arrange to pick up or meet deliveries.

If you see suspicious activity call 911 with a description or photographs including license plate numbers. If you cannot call immediately please use 1-877-ASK-LAPD.
Recently people have placed a sticky substance on the inside of chutes of the US Postal Mail Boxes.  This causes a letter to not drop inside but to remain stuck on the chute. Please be careful to check the box – and your checks to see if the amount and payee are correct. Criminals using check washing, like this “mail snatcher,” can erase the ink on a check and then rewrite the checks to themselves, increasing the amount payable as well. From SSA the advice is that only one type of ink, the kind in gel pens, has been found to be counterfeit proof to acetone or any other chemical used in “check washing.” Most ballpoint and marker inks are dye based, meaning that the pigments are dissolved in the ink.