[PHP-WIN] mail() function

[Marlene Burckhalter]

I am very new at this...

I want to use the mail funtion, but instead of using an actual e-mail address for the 
first argument, I want to pass it a variable that I have assigned to the resulting 
return of a function.  The fuction ends like this :

function get_useremail {...

$query_data = mysql_fetch_row($result);
      return $query_data[0];
   }

I then assigned the function to a variable:

$retrieveuseremail = get_useremail ($username, $userid);

WHEN I TRY TO USE $retrieveuseremail AS THE FIRST ARGUMENT IN THE MAIL FUNCTION, I GET 
AN ERROR MESSAGE :
Failed to receive in 'C:ThePathToTheDocument'

CAN I PASS A VARIABLE HERE?

Marlene