I had the same problem and only figured out the solution after trying all of the incorrect answers above. Please folks, don't assume that we all have a copy of LiveCycle. (Yes, this is the LIveCycle Forum, but this is a basic form distribution question. Maybe the discussion should be moved?)
This is a problem that wil occur when someone creates a distributed form for someone else, such as when the techie person in the office turns a paper form into a fillable form for the Ludditte administrative staff. Or, when only one person in an office has a copy of Adobe Pro 9 or 10, often only because they purchased the entire suite for other job tasks (web editing, etc.).
Acrobat Pro assumes that the person creating the form is the same person the form should be emailed back to when it is filled out. That's a stupid assumption, but there you go. The email address that the form is sent to is based on the Acrobat Pro user's "identity". On an Apple, you would go to Preferences, then select Identity from the laundry list on the left side. Temporarily change the Identity info to that of the person you'd like to have the filled-out forms returned to. Once you've done this, you can go back to the original form, step through the "Distribute Form" wizard and then post or distribute this new version.
When that's all done, insist that everyone who might need to create a form in the future get their own personal copy of Acrobat Pro and learn how to create a form themselves. ;-) Also, be sure to change the Identity information back.