dumb question port 25

[erice]

Just looking for it to be dumbed down
I have a basic contact forum
<p>
<?php
$msg = "Name:t$namen";
$msg .= "Email:t$emailn";
$msg .= "Comments:t$commentsn";
$recipient = "erice@mydomain.com";
$subject = "New Feedback from my site";
$mailheaders = "From:$emailn";
$mailheaders .= "Reply-To:$emailnn";
mail($recipient, $subject, $msg, $mailheaders);
header("Location: http://mydomain.com/contacttest/thankyou.html");
?>
</p>

put can not get it to go
I get the port 25 message
how do you redirect it not to use port 25
is it the hosting company blocking it or is it the internet provider "comcast" blocking it

[egami]

$mailed = mail($recipient,$subject,$msg,$mailheaders);
echo "MAILED RESULTS: $mailed";