Some genius out there started selling wooden postcards. They jam and break sorting machines. When 40,000 per hour ( I may have said per minute in a previous post, my bad) letters are whipping through a machine and one of those babies gets jammed about 50 other customers letters are going to get "folded, spindled or mutilated". Cassette tapes, keys, glasses and other inappropriate articles for envelopes can have the same effect.
For those that don't know the process. The mail you place in collection boxes gets picked up and moved to a distribution facility (except LOCAL MAIL). At 3pm or so the cancelling machines are started they run until 11 pm or so after midnites on the heavy days, (yesterday. monday before Mother's day, April 15th) The cancelling machines place a date over the stamp and face the mail all the same way. It also sprays a unique ID on the back. An electronic image of the address is sent to a bank of computers which try to "read" the address. Un readable images are sent to a video monitor where an employee keys in the unreadable address.
About 45 minutes after cancelling the mailpiece goes to another sorter, which sorts out mail for the region as well as mail outside of the region, a black posnet barcode is sprayed on the front of the mailpiece, this includes the recipients zipcode, carrier route and the stop on the route.
The local letters will continue to be sorted until the mail is staged in the order the carrier walks/drives the route. The theory is the carrier won't have to look at the mail.
Outside of the area mail is trayed and trucked to airports where it is sent to other distribution sites throughout the country.
At our plant we normally finish sorting around 7am, the whole process starts back up at 3pm.
Monday was our busiest "collection" day, that mail will be delivered on Tuesday - Thursday depending on the distance it has to travel.
Those bubble wrap envelopes are great for un machineable things, they are removed from automation without any problem. I spent an evening in the hospital because a test tube burst in an envelope that got jammed, an unknown liquid on my hands, turned out to be well water.
All in a day's work
Dave