i get 403 forbidden when trying to GET a request using https proxy

use warnings;
use strict;
use HTTP::Response;
use LWP::UserAgent;
use LWP::Debug qw(+);
use HTTP::Request;
use JSON;
use Data::Dumper;
use DateTime;


my ($ua,$url,$req,$res,$mail,$decode,$code,$jsond,$date,$startsec,$fin
+ishsec,$diffsec);
$mail = 'https://outlook.office365.com/api/v1.0/users/monitor@redoute.
+pt/messages/?$select=Sender,Subject';

$ua = LWP::UserAgent->new(keep_alive => 1,);
$ua->agent('Mozilla/5.0');
$ua->proxy(['https'], "http://172.25.193.52:8080");
$ua->timeout(1);

$req = HTTP::Request->new(GET => $mail);
$req->authorization_basic('login','pass');
$req->header(Host => 'outlook.office365.com');
$res = $ua->request($req);
print STDERR ("[DEBUG]: RESPONSE =" .Dumper \$res );
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