Could not authenticate Google account through PHPMailer - php

Question

I'm using PHPMailer in a Simple Script For Send Email's Through Gmail, and I'm getting an this error (I'm sure that the email and password combination is correct):
!-- 2020-12-02 14:13:16 CLIENT -> SERVER: EHLO localhost
2020-12-02 14:13:16 CLIENT -> SERVER: STARTTLS
2020-12-02 14:13:17 CLIENT -> SERVER: EHLO localhost
SMTP Error: Could not authenticate.
2020-12-02 14:13:17 CLIENT -> SERVER: QUIT
SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting
Allow less secure apps is ON
This is the way I implement the phpMailer
use PHPMailer\PHPMailer\Exception;
use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\SMTP;
require './mailer/autoload.php';
$msg = "";
$mail = new PHPMailer();
try {
//Server settings
$mail->SMTPDebug = SMTP::DEBUG_CLIENT;
$mail->isSMTP();
$mail->Host = 'smtp.google.com';
$mail->SMTPAuth = true;
$mail->Username = '********#gmail.com';
$mail->Password = '********';
$mail->SMTPSecure = "tls";
$mail->Port = 25;
$mail->CharSet= 'UTF-8';
$mail->setFrom('*******#gmail.com', 'Mailer');
$mail->addAddress($_POST["mail"]);
$mail->isHTML(true);
$mail->Subject = $_POST["subject"];
$mail->Body = '<h2>E-mail</h2>';
$mail->AltBody = $_POST["content"];
$mail->send();
} catch (Exception $e) {
$msg = "An Error has Ocurr";
}
How can I solve this issue?

Answer 1

SMTP port 25 is not used with TLS, you should use port 587 for TLS/STARTTLS or 456 for SSL. And it seems that you've also used the incorrect host URL, which should be smtp.google.com. The required configuration is stated here: https://support.google.com/mail/answer/7126229.
So you should probably change:
...
$mail->Host = 'smtp.google.com';
$mail->Port = 25;
...
To:
...
$mail->Host = 'smtp.gmail.com';
$mail->Port = 587;
...
Depending on your situation, it might not be best practice to use Google's default SMTP. It is OK for personal use, but if you want to send more automated emails, you should look for other options. The default Google SMTP is strictly rate limited for example.
First of all, Google SMTP Relay yields a little more configurability if you need it.
When you really want to send automated or bulk emails, you should look into a provider specifically for this. It is not what the Google SMTP servers are made for and you will quickly notice by emails not being sent out or delivered properly.

Answer 2

It would really help if you actually read the error message and took the advice it gives you, by reading the guide it links to.
First of all, you're only showing client debug output, so you can't see what the server is saying, and so you can't tell what's going on, as the docs say. Do this:
$mail->SMTPDebug = SMTP::DEBUG_SERVER;
Without seeing what that says, you're working blind.
That said, you get kicked out immediately after EHLO, and the only thing you have said is:
2020-12-02 14:13:17 CLIENT -> SERVER: EHLO localhost
Unfortunately this is untrue, and I'd guess that gmail is calling you out on it. localhost is by definition not an internet routable address, and any reverse lookup on the name will never match the IP you are connecting from, which is not localhost. If that is happening automatically, override it manually by setting the client host explicitly:
$mail->Helo = 'myhost.example.com';
While RFCs mandate port 587 for SMTP+STARTTLS, gmail supports it on port 25 too, and you can see that your STARTTLS command is working successfully, so that's not the problem here.

Answer 3

use port 587
$mail->IsSMTP();
$mail->SMTPDebug = 0;
$mail->SMTPAuth = true;
$mail->SMTPSecure = 'tls';
$mail->Host = "smtp.gmail.com";
$mail->Port = 587;
$mail->Username = '********#gmail.com';
$mail->Password = '********';