одна кнопка отправки для выполнения трех функций

<?php

$email_from = $_POST['email'];
$errors=array(); //track the errors as the script runs
function isValidEmail($addr) // Check for a valid email
{
return filter_var($addr, FILTER_VALIDATE_EMAIL) ? TRUE : FALSE;
}

if(!isValidEmail($email_from))$errors[]='Please enter a valid email address';

//Next, test for the email provider you wanted to filter by
$atPos=strpos($email_from,'@');//find the @ symbol
$afterAt=substr($email_from,$atPos,strlen($email_from)-$atPos); //get everything after
$dotPos=strpos($afterAt,'.');
$domain=strtolower(substr($afterAt,0,$dotPos)); //get the typed domain, lowercase
if($domain!='hotmail'||$domain!='gmail')$errors[]='Email must be hotmail or gmail';

if(isset($_POST['email'])) {

if(count($errors)<0)
{
$to      = '[email protected]';
$subject = '';
$email = $_POST['email_from'];
//$message = "LIST \r\n".
$message = "signoff list name \r\n";

// create email headers
$message = wordwrap($message, 100, "\r\n");
$headers = 'From: '.$email."\r\n".
'Reply-To: '.$email."\r\n" .
'X-Mailer: PHP/' . phpversion();
@mail($to, $subject, $message, $headers);
}
}// note that I changed the nesting to only trigger the mail on post
?>
<p>If you would like to receive our weekly newsletter email address below.</p>

<script type="text/javascript">
function IsEmpty(){
if(document.forms['isgtest'].email_from.value == "")
{
alert("Email field is empty, please enter email format");
return false;
}
//return submit "email_from.value";
(document.forms['test'].email_from.value == "subscribe")
//return .email_from.value == "";
//alert("thank u for joining the list !");
//return true;
}
</script>

<!--<script type="text/javascript"></script>-->

<?php
if(count($errors)>0)
{
foreach $errors as $e //Now tell the user what went wrong
{
echo "$e<br>"; // you can also use '' to enclose js tags and use alert
}
}
?>

<form name="isgtest" class="rform" method="post" action="g.php"> 
<fieldset><legend>testing...</legend> 

<label for="email_from"><span style="color: #ff0000;"><strong>*</strong>
</span>Email address:<input id="email_from" type="text" name="email_from" size="25" /><input id="insert" id="btn" onclick="return IsEmpty();" style="float: right;" type="button" name="submit" value="Subscribe" />  </fieldset>
</form>