The U.S. Postal Service has a warning to anyone planning on sending holiday cards or gifts to family and friends this year — do not drop them in the blue mailboxes. The department says reports of mail thefts have been on the rise and tend to peak during the holiday season. The majority of these thefts involve thieves reaching into blue mailboxes. The post office advises people to hand their cards and packages directly to their postal carrier or drop it in the box at the post office. If you have no other choice but to put it in a blue mailbox, try to do it right before the last collection of the day. Leaving it in the box overnight is a bad idea.