$userAgent = LWP::UserAgent->new(agent => 'perl post');
     
 $file_contents = do { local $/; <INFILE> };

    $message = $file_contents;
     
    $response = send_xml();


    $xml_resp = $response->as_string;


sub send_xml
{

    my $request = HTTP::Request->new(POST => 'http://"servername".asmx
+');
  $request->header(SOAPAction => "https://"url");
  $request->content($message);
    $request->content_type('text/xml; charset=utf-8');
  my $response = $userAgent->request($request);

  $response;
}
[download]

Why do you use $response->as_string instead of using $response->content or $response->decoded_content ? $response already is a HTTP::Response (which is a HTTP::Message), so you already have everything you need. You just should start using it.