Smtp error password command failed

I have used phpmailer() concept to send mail to users from my shared server using php script, but I’m not able to send even though everything is right in my script according to phpmailer code.

My code like this:

  $message = " This is testing message from my server";

  $mail = new PHPMailer(); // create a new object
  $mail->IsSMTP(); // enable SMTP
  $mail->Host = "smtp.gmail.com";
  $mail->SMTPDebug = 1; // debugging: 1 = errors and messages, 2 = messages only
  $mail->SMTPAuth = true; // authentication enabled
  $mail->SMTPSecure = 'ssl'; // secure transfer enabled REQUIRED for GMail
  $mail->Port = 465; // or 587
  $mail->IsHTML(true);
  $mail->Username = "moorthi.mrk10@gmail.com"; // My gmail username
  $mail->Password = "************"; // My Gmail Password
  $mail->SetFrom("moorthi.mrk10@gmail.com");
  $mail->Subject = "Test Mail from my Server";
  $mail->Body = $message;
  $mail->AddAddress($email);
   if($mail->Send())
      {
    print json_encode("SUCCESS");
}
else
{
    echo "Mailer Error: " . $mail->ErrorInfo;
    
}

Note: I have used » GMail » as my SMTP server and SMTPSecure is » ssl » and port is «465» and username & passwords are my GMail username & password

I used VPS shared server and I kept my php script on that server.

I think there is no problem in my php script and I don’t know why it doesn’t work.

I got the ERROR like this.

  2014-02-21 12:30:11   CLIENT -> SERVER: EHLO jkcorporates.com
  2014-02-21 12:30:11   CLIENT -> SERVER: AUTH LOGIN
  2014-02-21 12:30:11   CLIENT -> SERVER: bW9vcnRoaS5tcmsxMEBnbWFpbC5jb20=
  2014-02-21 12:30:11   CLIENT -> SERVER: OTk0MTI0MTE0MA==
  2014-02-21 12:30:11   SMTP ERROR: Password command failed: 534-5.7.14 
  534-5.7.14 i-_eumA> Please log in via your web browser and then try again.
  534 5.7.14 54 k76sm17979938yho.18 - gsmtp
  2014-02-21 12:30:11   CLIENT -> SERVER: QUIT
  " The ERROR is  "  SMTP connect() failed.

Please give some solution for that.

Remember: I use Shared Server Name ‘VPS.mydomain.com’ and I want to use GMail as my SMTP server to send mail to users.

I am unable to send an email with smtp
here is the code I am using

public function hello()
{
	require_once(APPPATH."libraries/phpmailer/PHPMailerAutoload.php");
	
	$mail = new phpmailer();
	//Tell PHPMailer to use SMTP
	$mail->isSMTP();
	$mail->CharSet = 'UTF-8';
	$mail->SMTPSecure = 'tls'; // or ssl
	$mail->SMTPAuth = true;
	$mail->SMTPDebug = 2;
	$mail->Debugoutput = 'html';
	$mail->Host = "smtp.zoho.com";
	$mail->Port = 25;// 25, 465 for ssl or 587 for tls
	$mail->Username = 'my_email@example.com';
	$mail->Password = 'my_password';
	$mail->setFrom('my_email@example.com','example.com');
	$mail->addReplyTo('my_email@example.com', 'example.com);
	$mail->addAddress('my_friend@gmail.com',"my_friend name");
	$mail->Subject = 'PHPMailer SMTP test from Hello';
	$mail->Body = 'Body This is a plain-text message body';
	$mail->AltBody = 'This is a plain-text message body';
	
	//send the message, check for errors
	if (!$mail->send()) {
	    echo "Mailer Error: " . $mail->ErrorInfo;
	} else {
	    echo "Message sent!";
	}

}

and this is what I get

2017-06-14 16:42:36 SERVER -> CLIENT: 220-server.example.com ESMTP Exim 4.86 #2 Wed, 14 Jun 2017 12:42:36 -0400 220-We do not authorize the use of this system to transport unsolicited, 220 and/or bulk e-mail.
2017-06-14 16:42:36 CLIENT -> SERVER: EHLO example.com
2017-06-14 16:42:36 SERVER -> CLIENT: 250-server.example.com Hello example.com [23.92.221.226]250-SIZE 52428800250-8BITMIME250-PIPELINING250-AUTH PLAIN LOGIN250-STARTTLS250 HELP
2017-06-14 16:42:36 CLIENT -> SERVER: STARTTLS
2017-06-14 16:42:36 SERVER -> CLIENT: 220 TLS go ahead
2017-06-14 16:42:36 CLIENT -> SERVER: EHLO example.com
2017-06-14 16:42:36 SERVER -> CLIENT: 250-server.example.com Hello example.com [23.92.221.226]250-SIZE 52428800250-8BITMIME250-PIPELINING250-AUTH PLAIN LOGIN250 HELP
2017-06-14 16:42:36 CLIENT -> SERVER: AUTH LOGIN
2017-06-14 16:42:36 SERVER -> CLIENT: 334 VXNlcm5hbxWUd
2017-06-14 16:42:36 CLIENT -> SERVER: bm9fcmVdbHddc2hvcddtZXJpa2EuY29t
2017-06-14 16:42:36 SERVER -> CLIENT: 334 UGdzc3dvdmQ6
2017-06-14 16:42:36 CLIENT -> SERVER: IXMxsdU1OTss
2017-06-14 16:42:38 SERVER -> CLIENT: 535 Incorrect authentication data
2017-06-14 16:42:38 SMTP ERROR: Password command failed: 535 Incorrect authentication data
SMTP Error: Could not authenticate.
2017-06-14 16:42:38 CLIENT -> SERVER: QUIT
2017-06-14 16:42:38 SERVER -> CLIENT: 221 server.example.com closing connection
SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting
Mailer Error: SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting

I have been looking on stackoverflow for days and nothing worked for me
I made a small Python script to send emails using smtplib and everything worked ok, but I need to use PHP. the error is vague. I also followed the Troubleshooting https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting
and everything is set properly in my dns
what can be wrong ? I even contacted zoho mail and they told me that the problem is in my code, which is true since the Python code works just fine .
thank you for your help

Stuck with PHPMailer – SMTP error password command failed? We can help you.

We may come across this error when we try to send mail using phpmailer().

SMTP ERROR: Password command failed: 534-5.7.14

As part of our Server Management Services, we assist our customers with several SMTP queries.

Today, let us see how to fix this error.

PHPMailer – SMTP error password command failed

This error may occur due to the below reasons:

• When a less secure application tries to use the email account.
• If we try to log in several times a row
• If we change countries (For example, use VPN, move code to a different server, or actually try to login from a different part of the world).

Moving ahead, let us see the methods our Support Techs employ in order to fix this.

Solution 1: In the case of the Windows server

PHP.ini

1. Initially, we go to C:xamppphp, edit the php.ini file with notepad.
2. Under the [mail munction] section, we remove the semicolon for this line:

   sendmail_path = “”C:xamppsendmailsendmail.exe” -t”

3. Then we add a semicolon for this line:

   sendmail_path=”C:xamppmailtodiskmailtodisk.exe”

SendMail.ini

1. Here, we go to C:xamppsendmail, edit the sendmail.ini file with notepad
2. Then we change the following:

   smtp_server=smtp.gmail.com
   smtp_port=465
   auth_username=your-gmail-username@gmail.com
   auth_password=your-gmail-password
   force_sender=your-gmail-username@gmail.com

smtp_port should tally with what is written in our php code.

Solution 2: Enable less secure applications (SMTP server is Gmail)

1. Initially, we login to the account via web
2. Then we view recent attempts to use the account and accept suspicious access:
   https://security.google.com/settings/security/activity?hl=en&pli=1
3. We can disable the feature of blocking suspicious apps/technologies:
   https://www.google.com/settings/u/1/security/lesssecureapps

Solution 3: (SMTP server is Gmail)

1. Initially, login to the account via web
2. Access the URL: https://accounts.google.com/b/0/DisplayUnlockCaptcha
3. Then we click the continue option
4. We can check whether phpmailer is set as SMTP with SSL.

This will work if our SMTP server is Gmail.

Solution 4: Change SMTPSecure value from SSL to TLS in phpmailer() code.

Solution 5: In the case of Gsuite

In such a case, we have to solve it as the Administrator.

1. Go to Admin panel >> Security with Shield icon >> Basic settings
2. Then go to the Less secure apps section
3. Now we select one of the Radio Button:

a) Disable access to less secure apps for all users (Recommended)
b) Allow users to manage their access to less secure apps
c) Enforce access to less secure apps for all users (Not Recommended)

Generally, if option a) does not work, it will start to work with the c) option.

Solution 6: In the case of cPanel/WHM servers

This is related to a security feature in WHM/cPanel.

1. Firstly, log in to CPanel
2. Navigate to Tweak Settings > All > “Restrict outgoing SMTP to root, Exim, and mailman”
3. Eventually, switch it from “On” to “Off”.

In addition, we can do this via SSH as well:

/scripts/smtpmailgidonly off

[Need help with the solution? We’d be happy to assist]

Conclusion

In short, today, we saw how our Support techs resolve the SMTP error.

var google_conversion_label = «owonCMyG5nEQ0aD71QM»;

Sometimes we can encounter this SMTP error when we try to send mail using phpmailer():

SMTP ERROR: Password command failed: 534-5.7.14

Here at Ibmi Media, as part of our Server Management Services, we regularly help our Customers to perform related SMTP queries.

In this context, we shall look into methods to resolve this error.

Nature of PHPMailer SMTP error password command failed

Basically, this error happens as a result of the following reasons:

1. When a less secure application tries to use the email account.

2. If we try to log in several times a row

3. If we change countries (For example, use VPN, move code to a different server, or actually try to login from a different part of the world).

Now, lets see how to resolve this error.

Solution 1: In the case of the Windows server

a. PHP.ini

i. Initially, we go to C:xamppphp, edit the php.ini file with notepad.

ii. Under the [mail munction] section, we remove the semicolon for this line:

sendmail_path = “”C:xamppsendmailsendmail.exe” -t”

iii. Then we add a semicolon for this line:

sendmail_path=”C:xamppmailtodiskmailtodisk.exe”

b. SendMail.ini

i. Here, we go to C:xamppsendmail, edit the sendmail.ini file with notepad

ii. Then we change the following:

smtp_server=smtp.gmail.com
smtp_port=465
auth_username=your-gmail-username@gmail.com
auth_password=your-gmail-password
force_sender=your-gmail-username@gmail.com

smtp_port should tally with what is written in our php code.

Solution 2: Enable less secure applications (SMTP server is Gmail)

i. Initially, we login to the account via web

ii. Then we view recent attempts to use the account and accept suspicious access:

https://security.google.com/settings/security/activity?hl=en&pli=1

iii. We can disable the feature of blocking suspicious apps/technologies:

https://www.google.com/settings/u/1/security/lesssecureapps

Solution 3: (SMTP server is Gmail)

i. Initially, login to the account via web

ii. Access the URL: https://accounts.google.com/b/0/DisplayUnlockCaptcha

iii. Then we click the continue option

iv. We can check whether phpmailer is set as SMTP with SSL.

This will work if our SMTP server is Gmail.

Solution 4: Change SMTPSecure value from SSL to TLS in phpmailer() code.

Solution 5: In the case of Gsuite

In such a case, we have to solve it as the Administrator.

i. Go to Admin panel >> Security with Shield icon >> Basic settings

ii. Then go to the Less secure apps section

iii. Now we select one of the Radio Button:

a) Disable access to less secure apps for all users (Recommended).

b) Allow users to manage their access to less secure apps.

c) Enforce access to less secure apps for all users (Not Recommended).

Generally, if option a) does not work, it will start to work with the c) option.

Solution 6: In the case of cPanel/WHM servers

This is related to a security feature in WHM/cPanel.

i. Firstly, log in to CPanel.

ii. Navigate to Tweak Settings > All > «Restrict outgoing SMTP to root, Exim, and mailman».

iii. Eventually, switch it from «On» to «Off».

In addition, we can do this via SSH as well:

/scripts/smtpmailgidonly off

[Need help with the solution to this SMTP error? We’d be happy to assist. ]

The author voluntarily contributed this tutorial as a part of Pepipost Write to Contribute program.

Introduction

In this tutorial, you will learn how to send email in PHP using PHPMailer library via Gmail SMTP.  Like PHPMailer, there are few more good email sending libraries in PHP e.g. PEAR::Mail interface, Swiftmailer etc which can help you easily send mail in PHP using Gmail SMTP.

Prerequisites

Before starting with steps on how to send mail using SMTP in PHP example, lets first see what are few limits with Gmail SMTP servers and how to overcome some of these:

• Gmail limits the number of recipients in a single email and the number of emails that can be sent per day. The current limit is 500 Emails in a day or 500 recipients in a single email. You can’t really increase this limit. If you want to send above these limit, then you need to integrate with third-party email delivery platform like Pepipost Sendgrid etc.
• On reaching threshold limits, you won’t be able to send messages for the next 24 hours. Once this temporary suspension period is over, the counter gets reset automatically, and the user can resume sending emails.
• By default, any third-party apps/codes are not allowed to send emails using your Gmail account. And, hence there are few settings which need to be done at your end:

How To Enable Email Sending In Gmail?

1. Before sending emails using the Gmail’s SMTP Server, you to make some of the security and permission level settings under your Google Account Security Settings.
2. Make sure that 2-Step-Verification is disabled.
3. Turn ON the «Less Secure App» access or click here.
4. If 2-step-verification is enabled, then you will have to create app password for your application or device.
5. For security measures, Google may require you to complete this additional step while signing-in. Click here to allow access to your Google account using the new device/app.

Note: It may take an hour or more to reflect any security changes

Writing the PHP Code to Send Email using Gmail SMTP

Step 1:  Download PHPMailer library from this github link. To directly download the .zip file, use this link.

Unzip the master.zip in your application directory and run following command from your application directory.

composer require phpmailer/phpmailer

Composer is the recommended way to install PHPMailer.

Step 2: Writing the PHP Code to make an SMTP connection

• Using your Gmail credentials, connect to host «smtp.gmail.com»
• Click here for some more Examples and Tutorials of PHPMailer

Step 3: Include packages and files for PHPMailer and SMTP protocol:

use PHPMailerPHPMailerPHPMailer;
use PHPMailerPHPMailerException;
require 'PHPMailer-master/src/Exception.php';
require 'PHPMailer-master/src/PHPMailer.php';
require 'PHPMailer-master/src/SMTP.php';

Step 4: Initialize PHP Mailer and set SMTP as mailing protocol:

$mail = new PHPMailer();
$mail->IsSMTP();
$mail->Mailer = "smtp";

Step 5: Set required parameters for making an SMTP connection like server, port and account credentials. SSL and TLS are both cryptographic protocols that provide authentication and data encryption between servers, machines and applications operating over a network. SSL is the predecessor to TLS.

$mail->SMTPDebug  = 1;  
$mail->SMTPAuth   = TRUE;
$mail->SMTPSecure = "tls";
$mail->Port       = 587;
$mail->Host       = "smtp.gmail.com";
$mail->Username   = "[email protected]";
$mail->Password   = "your-gmail-password";

Step 6: Set the required parameters for email header and body:

$mail->IsHTML(true);
$mail->AddAddress("[email protected]", "recipient-name");
$mail->SetFrom("[email protected]", "from-name");
$mail->AddReplyTo("[email protected]", "reply-to-name");
$mail->AddCC("[email protected]", "cc-recipient-name");
$mail->Subject = "Test is Test Email sent via Gmail SMTP Server using PHP Mailer";
$content = "<b>This is a Test Email sent via Gmail SMTP Server using PHP mailer class.</b>";

Step 7: Send the email and catch required exceptions:

$mail->MsgHTML($content); 
if(!$mail->Send()) {
  echo "Error while sending Email.";
  var_dump($mail);
} else {
  echo "Email sent successfully";
}

Working PHP Code to Send Email Using SMTP Server

Click here to download the complete working PHP code to send email using Gmail SMTP server. You need to just change a few values and it should work.

List of Possible Errors And Exceptions

Error 1: Password Command Failed: 534-5.7.9 Application-Specific Password Required🔗

SMTP ERROR: Password command failed: 534-5.7.9 Application-specific password required. Learn more at 534 5.7.9  https://support.google.com/mail/?p=InvalidSecondFactor z2sm11041738pfq.58 - gsmtp
SMTP Error: Could not authenticate.
CLIENT -> SERVER: QUIT
SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting
Problem sending email.

This happens mostly when SMTP Mail Server Credentials were correct but Application Specific Password was not provided.

Error 2: SMTP ERROR: Password Command Failed: 535-5.7.8 Username And Password Not Accepted🔗

SMTP ERROR: Password command failed: 535-5.7.8 Username and Password not accepted. Learn more at 535 5.7.8  https://support.google.com/mail/?p=BadCredentials f3sm5807314pgj.62 - gsmtp
SMTP Error: Could not authenticate.
CLIENT -> SERVER: QUIT
SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting
Problem sending email.

If you have encountered this error, then this is mostly because the application specific password is incorrect.

Error 3: Invalid Address: (To): Recipient-Email🔗

Invalid address:  (to): recipient-email
Problem sending email.

If you have encountered this error, then this is mostly because the recipient email is invalid.

Error 4: SMTP: SMTP Server Does No Support Authentication🔗

authentication failure [SMTP: SMTP server does no support authentication (code: 250, response: mx.google.com at your service, [98.117.99.235] SIZE 35651584 8BITMIME STARTTLS ENHANCEDSTATUSCODES PIPELINING)]

If you have encountered this error, then this is mostly because your code does not appear to be using TLS/SSL, which is necessary to deliver mail to Google , also you should be using port 587 or 465.

Reconfirm once whether the value of $host is set as follows:

$host = "ssl://smtp.gmail.com";

Error 5: Stream_socket_client(): Unable To Connect To Smtp.Gmail.Com🔗

Error on Feb 25, 2018 11:14AM - stream_socket_client(): unable to connect to smtp.gmail.com:587 (Connection timed out) in /home/dibya/public_html/dibyasahoo/app/helpers/phpmailer/smtp.php on line 222

If you have encountered this error, then this is mostly because your server cannot connect to smtp.gmail.com on port 587. This is mostly because your hosting provider has some strict firewall rule which is blocking your server to connect to any other external server over SMTP port 587.

Error 6: SMTP Server Error: 5.5.1 Authentication Required. Learn More At 530 5.5.1🔗

SMTP server error: 5.5.1 Authentication Required. Learn more at 530 5.5.1 

If you have encountered this error, then this is mostly because you have enabled 2FA on your Gmail account or you have not enabled access to Less Secure App. Read the above prerequisites to address this problem.

Error 7: Message: Fsockopen(): Unable To Connect To Ssl://Smtp.Gmail.Com🔗

Message: fsockopen(): unable to connect to ssl://smtp.gmail.com:25 (A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond. )

If you have encountered this error, then this is mostly because of SSL issue. You need to enable SSL in php.ini file of your server configuration. In case you are using a XAMPP server, then please check whether it is enabled or not. You will get that in PHP info.

Error 8: Emails from PHP code going in Spam

Defintely this is not an error, but definitely a point of concern. One of the most common reason of emails landing in spam is blacklisting. You should check whether your domain or IP address is blacklisted.

Debugger step-by-step output after sending email successfully

CLIENT -> SERVER: EHLO NL616
CLIENT -> SERVER: STARTTLS
CLIENT -> SERVER: EHLO NL616
CLIENT -> SERVER: AUTH LOGIN
CLIENT -> SERVER: <credentials hidden>
CLIENT -> SERVER: <credentials hidden>
CLIENT -> SERVER: MAIL FROM:<[email protected]>
CLIENT -> SERVER: RCPT TO:<[email protected]>
CLIENT -> SERVER: RCPT TO:<[email protected]>
CLIENT -> SERVER: DATA
CLIENT -> SERVER: Date: Sun, 22 Sep 2019 05:11:15 +0000
CLIENT -> SERVER: To: recipient-name <[email protected]>
CLIENT -> SERVER: From: PHP SMTP Mailer <[email protected]>
CLIENT -> SERVER: Cc: cc-recipient-name <[email protected]>
CLIENT -> SERVER: Reply-To: reply-to-name <[email protected]>
CLIENT -> SERVER: Subject: Test email using PHP mailer
CLIENT -> SERVER: Message-ID: <[email protected]>
CLIENT -> SERVER: X-Mailer: PHPMailer 6.0.7 (https://github.com/PHPMailer/PHPMailer)
CLIENT -> SERVER: MIME-Version: 1.0
CLIENT -> SERVER: Content-Type: multipart/alternative;
CLIENT -> SERVER:  boundary="b1_UlnH3mCpHcFVNBY3Lb3PR2tVs6tvdJlu2F8g5sPN4"
CLIENT -> SERVER: Content-Transfer-Encoding: 8bit
CLIENT -> SERVER: This is a multi-part message in MIME format.
CLIENT -> SERVER: --b1_UlnH3mCpHcFVNBY3Lb3PR2tVs6tvdJlu2F8g5sPN4
CLIENT -> SERVER: Content-Type: text/plain; charset=us-ascii
CLIENT -> SERVER: This is a test email using PHP mailer class.
CLIENT -> SERVER: --b1_UlnH3mCpHcFVNBY3Lb3PR2tVs6tvdJlu2F8g5sPN4
CLIENT -> SERVER: Content-Type: text/html; charset=us-ascii
CLIENT -> SERVER: <b>This is a test email using PHP mailer class.</b>
CLIENT -> SERVER: --b1_UlnH3mCpHcFVNBY3Lb3PR2tVs6tvdJlu2F8g5sPN4--
CLIENT -> SERVER: QUIT
email sent.

Conclusion

Hope the steps explained above were useful and you were able to successfully send mail from your Gmail SMTP server using PHP. Feel free to contribute, in case you encountered some issue which is not listed as a part of this tutorial. Use below comments section to ask/share any feedback.

<? Happy Coding ?>

What is an SMTP Error Code?

When you sent a message from a mail client via the SMTP server, the server will reply with a specific response code. This response is a normal part of the email sending process and is an essential step in getting your email to the sent.

An SMTP(Simple Mail Transfer Protocol), a three-digit code response code between two servers to communicate throughout the email sending process

These types of response codes can be useful to verify the errors and debug it, like 250, or it can indicate that there was a communication error.

If there is a communication error, you will receive an SMTP error code — a message that indicates the specific problem; like the end of server communication, which is error code 550 (The request failed).

Positive SMTP Response Codes

Generally, Positive SMTP response codes start with regular 2 and 3, that doesn’t indicate an error.

SMTP 200 Response Codes

• 220 – SMTP server is ready to sent emails
• 221 – SMTP server is closing its transmission channel
• 250 – requested action is accepted and triggered (Good news!)

SMTP 300 Response Codes

A response code starting with 3 indicates the request is identified, but the server needs more information to complete the task.

• 334 – SMTP authentication credentials is Invalid.
• 354 – Waiting for the email message contents

SMTP Server Error Messages

SMTP 400 Error Codes

Error code 4 means the server is facing a temporary failure.if the server tried again, the process might be completed. Error codes starting with 4 are typical errors related to the mail system(receiver).

Note: Response codes starting with 4 and 5 indicates that an error has occurred onto the system.

• 421 – Email service is unavailable. Wait for some interval and try again.
• 450 – user’s mailbox was unavailable hence requested action was not taken
• 451 – Email not sent because of server error
• 452 – Storage Full and command aborted
• 455 – Server cannot trigger command this time

SMTP 500 Error Codes

The most prominent SMTP error code indicator starts with error code, 5.  If you notice this type of failure then, this is a permanent. Here are few examples:

• 500 – Syntax error, Server could not recognize the command
• 501 – Syntax error, Invalid arguments or parameters
• 502 – Command cannot be triggered
• 503 – Invalid sequence of server commands
• 541 – Receipient address rejected the email
• 550 – Requested command failed due to the receipient mail server was unavailable or the server rejected the email because of spam high probability
• 551 – Recipient address not found on the server
• 552 – Recipient address does not have adequate storage, hence message was not sent
• 553 – Command aborted because the mailbox name does not exist.
• 554 – The transaction failed. No further details are given.

How Do You Fix an SMTP Error?

These are few SMTP error codes, and there are many more that you will likely come across. Hence, most high volume email senders will work with email service providers.

Step 1

The solution was to enable outgoing SMTP from the server settings.

On servers running cPanel’s WHM, this is located under WHM’s “Tweak Settings” section.

The option is to enable/disable – choose disable.

Caveat: Making this change will redirect outgoing SMTP connections allow accounts to make direct connections, which may increase your odds of getting your server blacklisted.

Step 2

Restrict outgoing SMTP to root, Exim, and mailman (FKA SMTP Tweak)

Login to CPanel > Tweak Settings > All> “Restrict outgoing SMTP to root, Exim, and mailman (FKA SMTP Tweak) and switch it from “On” to “Off.”

for my case, I used the shell (ssh) to fix this :

/scripts/smtpmailgidonly off

Output

“SMTP Mail protection has been disabled. All users may make outbound SMTP connections.”