It seems Millennials are having a hard time dealing with snail mail -- and it's affecting their finances. Because they're so used to everything being done digitally, young adults aren't doing a very good job of checking their actual mailbox every day and often throw away stuff they need -- like bills and other important financial documents. They end up paying bills late -- and incurring late fees. They're also not paying close enough attention to other financial details being sent to them by the Post Office.