I write you an email. = Píšu Ti email.
I send you a letter. = Posílám Ti dopis.
I give you money. = Dávám Tí peníze.

I write an email to you. = Píšu email Tobě.
I send a letter to you. = Posílám dopis Tobě.
I give money to you. = Dávám peníze Tobě.

I send it to you. = Posílám Ti ho. (ho = dopis)
I give it to you. = Dám Ti je. (je = peníze)
I write it to you. = Napíšu Ti ho. (ho = email)