Help with template file and email

["Joey Hendricks" <j.hendricksjr@xxxxxxxxxxx>]

Hello,
  I have been working on a birtday invite program. The form takes 10 names and 10 email addresses. I think the problem is the $to variable in my function. I get this warning-Warning: mail() [function.mail]: SMTP server response: 550 5.5.0 <f> domain name required in.....
Could someone help me with this my email is j.hendricksjr@xxxxxxxxxxx Thank you so very much!
This is my code-

<?php
function mail_message($data_array, $template_file, $deadline_str)
{
$email_message = file_get_contents($template_file);
$email_message = str_replace("#DEADLINE#", $deadline_str, $email_message);
$email_message = str_replace("#DATE#", date("F d, Y h:i a"), $email_message);
$email_message = str_replace("#NAME#", $data_array['name'], $email_message);
//I tried many things for this $to variable
//If I put in an email address it works
$to=$mymail;
$from='j.hendricksjr@xxxxxxxxxxx';
$email_subject='Bubs Birthday';
 mail($to, $email_subject, $email_message, "From: ".$from);
 }
if(empty($_GET['name0']) && (empty($_GET['email0'])))
{
   $query_string = $_SERVER['QUERY_STRING'];
   $url = "invite_form.php?".$query_string."&error=1";
   header("Location: ".$url);
   exit();
}
for($i=0;$i<=9;$i++)
{
if(!empty($_GET[name.$i]) && (empty($_GET[email.$i])))
{
$query_string = $_SERVER['QUERY_STRING'];
   $url = "invite_form.php?".$query_string."&error=2";
   header("Location: ".$url);
   exit();
}
 }
for($i=0;$i<=9;$i++)
{
if(empty($_GET[name.$i]) && (!empty($_GET[email.$i])))
{
$query_string = $_SERVER['QUERY_STRING'];
   $url = "invite_form.php?".$query_string."&error=3";
   header("Location: ".$url);
   exit();
}
 }
function goodmail($myemail)
{
$goodemail="^([0-9a-zA-Z]+[-._+&amp;])*[0-9a-zA-Z]+@([-0-9a-zA-Z]+[.])+[a-zA-Z]{2,6}$";
 if(!ereg($goodemail, $myemail))
 {
 $query_string = $_SERVER['QUERY_STRING'];
    $url = "invite_form.php?".$query_string."&error=4";
    header("Location: ".$url);
   exit();
 }
return $myemail;
}
for($i=0;$i<=9;$i++)
{
if(!empty($_GET[email.$i]))
{
$mail=$_GET[email.$i];
goodmail($mail);
}
 }
extract($_GET, EXTR_PREFIX_SAME, "get");
for($i=0;$i<=9;$i++)
{
$deadline_array = getdate();
$deadline_day = $deadline_array['mday'] + 7;
$deadline_stamp = mktime($deadline_array['hours'],$deadline_array['minutes'],$deadline_array['seconds'],
$deadline_array['mon'],$deadline_day,$deadline_array['year']);
$deadline_str = date("F d, Y", $deadline_stamp);

if(!empty($_GET[email.$i]))
{
mail_message($_GET[email.$i], "email_template.txt", $deadline_str);
//mail($to, $email_subject, $email_message, "From: ".$from);
}
 }