Just to clear up any confusion:
My aunt is writing = Η θεία μου γράφει
The aunt is writing to me = Η θεία μού γράφει
When a dative pronoun (to me, to you, etc.) could also be mistaken for a possessive pronoun (my, your, etc.), it is accented. Remember: if a monosyllabic pronoun is accented it is dative.
Source (in Greek): http://ebooks.edu.gr/modules/ebook/show.php/DSDIM-F102/651/4161,19326/ Β7
I don't think that's right; English "me" can be used as an indirect object as well.
"She wrote me last week" means that I was the recipient of her message, not that I was the message itself.
You can also say "She wrote to me last week" but you can also say it without the "to".