Apparently I am causing spam with this script?

[vaaaska]

I've been told by my webhost, who is rarely correct on things, that my simple little script is the culprit of spam being created from my site. Perhaps it's so, but could somebody tell me how this little script could be used to cause spam (except to myself)...

if ($_POST['sub']) {
$headers .= "From: <$email>\r\n";
$headers .= "Reply-To: <$email>\r\n";
$headers .= "Return-Path: <[e-mail]>\r\n";

$msg = "Subscribe: $email";
mail ("[e-mail]","SUBSCRIBE",$msg,$headers);
header("location:subscribe.php?a=thanks");
}
if ($_POST['unsub']) {
$headers .= "From: <$email>\r\n";
$headers .= "Reply-To: <$email>\r\n";
$headers .= "Return-Path: <[e-mail]>\r\n";
$msg = "Unsubscribe: $email - $ip";
mail ("[e-mail]","UNSUBSCRIBE",$msg,$headers);
header("location:subscribe.php?a=thanks");
}

[nemonoman]

Many spam detectors use the word 'unsubscribe' as test for spam. Your message is probably triggering a false positive report.

[vaaaska]

But, how would this allow a spammer to spam more people than just me?

[dnszero]

You need to do email verification. Otherwise someone could just fill out your form with someone else's email addr.

That's the only spam opportunity that I see offhand.