I am using the Zenpage theme, with the regular contact form plug-in. When the form loads, the required field for the sender's email is already filled - with the email address to which all mail from the ZP site is to be sent!

The site is not live yet, but I can't seem to figure out how this might have happened.

You're still connect to the administration.

Laurent

If a user is logged in the software is smart enough to use his user information. If a guest visits those fields will be empty.

The best is always to test with two different browsers, one loggedin and one not.