Send post information to current page?

Hi,

I have a very simple “Join our mailing list” form in the head of my blog that consists of a text input box and a submit button. I want the page to submit the information to itself and right now I have the action set to “header.php” which successfully sends an email but results in a “404” page coming up.

Can anyone tell me how I get wordpress to submit post information to the current page? Perhaps some variable that I would put in the action field?

Thanks for any advice.