Believe it or not they have a system where as you are either a regular or a non-regular. A regular gets all the benefits such as health, paid holidays, fixed hours/schedule, much more vacation days, more sick days, and much more pay. They do not have to do the more physical demanding jobs such as off-loading the trucks or distributing the weekly ads (known as Advo's). A non-regular does the same as a regular, but also the previously mentioned physical demanding tasks. They have no paid holidays other than Christmas and New Year's, no health benefits, no official schedule, much lower pay. It takes many years to become a regular. The USPS is in no hurry to make you a regular.
No benefits, no retirement, bad health care, terrible hours, pay not worth the work, seniority based, takes years to move up, then right when you think you have a career position someone transfers and takes it. Older employees get paid twice as much as you do half the work and get tons of sick and vacation pay. They will never retire because they have it to easy and have the new, younger employees to do all their work. Terrible le system, union is terrible as well.