When it absolutely never has to get there in your lifetime.
yesterday I sent in my revised manuscript overnight with a noon guaranteed delivery. Not cheap. So my editor emailed tonight to tell me that it never arrived! I check the tracking number online, and it says a delivery attempt was made and a failed attempt notice left at the address. Will attempt second delivery tomorrow. Okay, this is a publishing house. I waived the signature. How can they not deliver a package at 10:36 a.m.? I'm guessing some clown was running late and didn't even attempt the delivery. Just said he did. Or he didn't know where the mail room was and stuck the notice on the revolving door. Idiot.