Microsoft 365 SMTP authentication failure [SMTP: Invalid response code received from server - smtp

Question

i am getting following error but all settings are correct no issue but advice if someone has done smtp setting of 365 office
connectors are added in admin center and changed the max sp as advised
authentication failure [
SMTP: Invalid response code received from server
(code: 535, response: 5.7.3 Authentication unsuccessful
[LO2P265CA0220.GBRP265.PROD.OUTLOOK.COM]
)
]
here is code:
<?php
require_once "Mail.php";
$from = '<info#domain.com>';
$to = '<dodmaon#domani.com>';
$subject = 'Insert subject here';
$body = "Hello world! this is the content of the email";
$headers = array(
'From' => $from,
'To' => $to,
'Subject' => $subject
);
$smtp = Mail::factory('smtp', array(
'host' => 'smtp.office365.com',
'SMTPSecure' => 'tls',
'port' => '587',
'StartTLS' => true,
'auth' => true,
'username' => 'info#domain.com',
'password' => '321password'
));
$mail = $smtp->send($to, $headers, $body);
if (PEAR::isError($mail)) {
echo '<p>'.$mail->getMessage().'</p>';
} else {
echo '<p>Message successfully sent!</p>';
}
?>

Answer 1

If you are very sure that all settings including Username and Password are correctly configured, then the problem is a Microsoft thing. And how to solve it is this;
you need to login from a browser (https://accounts.live.com) using the username and password you have configured in your application.
While logged in, go to "security and privacy" and look for the link to "recent activity" alternatively, you can just enter this address after logging in to go there directly https://account.live.com/Activity.
From here you should see the attempts from the email you are sending from and click the option "This was me" next/under to it.
Also consider disabling 2step authenticator if on.
When you have completed this, wait a few minutes and then try again.
Let me know if this worked. :)