Because Gold wants to get rid of Henry, and by teaming up with her (Tamara) he can get rid of him he wouldn’t be threaten with her power. Emma intercepts the note and it can’t be from Hook, if she is intercepting it. In other words if Hook wanted to give it to Emma why not just hand it over.
Plus like I said they list looks like it came from any old typewriter or something and Gold has a lot of stuff in his shop.
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