To whom should it be addressed

What's the best way to ask "To whom should the letter be addressed?" It's a fairly formal way of asking, but that's what I need and why I'm not sure...

You just write:
"Sehr geehrte Damen und Herren"
if you are unsure to whom you should address the letter.

Yeah, but I already have contact with the company, I want to know who to send the bills to.

And I don't appreciate the mods changing my title to crappy English. To WHOM, thanks very much.

Ah... that's better.

"An wen soll der Brief gehen" or
"An wen soll der Brief adressiert werden"

Probably easier to just call.

Wem soll ich die Rechnungen schicken?

or just call them and ask, as Gen said