Etiquette: Calling those who don't RSVP?

[Kate]

I've heard both sides of this one... and I don't know what to do!

1. don't call people that haven't returned their RSVP's and take it as they aren't coming; it's rude; it looks like you're trying to drum up business for your reception

2. call people that haven't returned their RSVP's because you don't want them to show up and not have a place to sit or food to eat; they may not have forgotten to send it back

What's right?

What does wedding etiquette say?

Thanks in advance.