Is a signature required for registered airmail if it is delivered to a locked mailbox in an apartment building?

I am not able to sign for packages during the day? Would this be dropped off without signature because it is in a locked mailbox that the postal worker has access to or would I still have to sign for it. Thanks.

Registered airmail does require a signature. If you miss them the 1st time around you may be able to leave the card in your box for the postal worker that allows for another party to sign in your absence.