Letter in the wrong slot

Question

I was supposed to mail a letter to Drexel University but i messed up at the post office and put it in the "local" slot (only for that town) rather then the "out of town" slot.

Is there a failsafe in the mail sorter or is the letter gone for good? I don't think there was a return address on it

Answer 1

Sorry, letters placed in the wrong slot fall into a black hole and are never seen again.

Answer 2

It will get spotted but delivery might be delayed slightly. Don't worry.