I am using a hidden field to pass to formmail empty optional fields if the users let them blank.
The problem is that when a user fills out one of these optional fields the hidden values adds up to the user specified value.
<input type="hidden" name="foo" value="not specified" />
<input type="text" name="foo" value="" />
results in

foo: not specified
when the user leaves the field blank; if the user fills out the field with the value "Hello", the final submitted value is:
foo: not specified Hello
How to remove the "not specified" string from user specified values and leave it just for empty submissions?

Thanks in advance!