Forbidden Email Names?

Sorry, couldn't find any specific place to ask this except here as the closest thing.

I was trying to create a mailbox "administrator" @domain.com. But I get a message
saying something like "this name is forbidden".

Asking my hosting provider revealed nothing. Forbidden Email Names?

I decided to google around, but even that's not giving me the specific answers I'm
seeking.

Thus, I wonder if you guys know if there's a list of names that aren't allowed to be
used for emailboxes like administrator. Is this some RFC or something?

Thanks.

 

 

 

 

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