Coe - Sign at door?

I have applied for a COE.

I am very nervous because I missed the door for a signed package from the embassy in Japan.

It took quite a while to get to me (4 months) because they called for some extra documents I had to provide (which I did, shortly after).

What does it mean when you have to sign at the door? Did I get rejected?
Or will I have to suck it up and wait until tomorrow to find out?

Has anyone else got rejected or accepted for a COE before? Did you have to sign at the door or was it just placed in your mailbox?

Maybe they sent it via registered mail for security?

It must be sent by the registered mail as above post said. You should sign to receive it.

What do you mean you missed the door?
You were not at home? Or you were at home but didn’t answer the door?
Anyway, did the delivery person leave any slip or postcard? （delivery notice 不在通知）
If so, you should contact the delivery company to deliver it again.
Usually delivery company try to deliver again later or keep the undelivered mail about 2 weeks (depending on the company) and if no response from the receiver, they will send back to the sender.