I've only had minor problems, mostly mail going to a neighbor or coming a few days later. The office is another story, they just cannot get the mail there during office hours, which is making a lot of businesses irate.
I do know that the problems started long before 2006. My father worked there after he came home from the navy until he retired, another friend retired from their (both forced into early retirement) and another friend works there. Dad's retirement pay got cut drastically in the late '90's with some lame excuse. He was originally told he could take early retirement and it would end up being better for him, same for retired friend.
Before that, many years before, the break down began with the machines. The machines that sort mail. When all of that started, the intended purpose was fewer employees, fewer wages paid, benefits paid, etc... and faster service. Those machines cost a whole heck of a lot of money, and at first, were full of problems.
Now they have fewer employees, and fewer each few weeks. They have added so much to any workers route that they cannot deliver it all in one day. They also keep changing their routes, am not certain why that is. Benefits have been cut a great deal, overtime is greatly frowned upon. These people are not machines and cannot do it all within any specified time frame. Hence the backed up mail, some in this area over a month old (being bulk mail a.k.a. junk mail) and employees that just do not feel like giving 120% anymore. Meaning just choosing not deliver it, which happens more than anyone wants to know, and, choosing not to work themselves into the ground when they cannot possibly get it all done.