Warning: mail(): Multiple or malformed newlines found in additional_header

[jolquera]

Hola, tengo esta función en php

function sendHTMLemail($HTML,$from,$to,$subject) {
$eol = PHP_EOL;
$headers = "From: $from".$eol;
$headers .= "Reply-To: $from".$eol;
$headers .= "Return-Path: $from".$eol;
$headers .= "X-Mailer: PHP/" . phpversion();
$headers .= "MIME-Version: 1.0".$eol;
$boundary = uniqid("HTMLEMAIL");
$headers .= "Content-Type: multipart/alternative;".
"boundary = $boundary".$eol.$eol;
$headers .= "This is a MIME encoded message.".$eol.$eol;
$headers .= "--$boundary".$eol.
"Content-Type: text/plain; charset=UTF-8".$eol.
"Content-Transfer-Encoding: base64".$eol.$eol;
$headers .= chunk_split(base64_encode(strip_tags($HTML)));
$headers .= "--$boundary".$eol.
"Content-Type: text/html; charset=UTF-8".$eol.
"Content-Transfer-Encoding: base64".$eol.$eol;
$headers .= chunk_split(base64_encode($HTML));
mail($to,$subject,"",$headers);
}

la cual me arroja el siguiente mensaje...

Warning: mail(): Multiple or malformed newlines found in additional_header in

Tengo entendido que por una actualización ya no se permite n/ ni r/