After having some issues sending Notifications to users I've decided to update PHPMailer to the latest version:
Here are the steps:

1) Update latest version of PHPMailer:
Downlaod phpmailer from https://github.com/PHPMailer/PHPMailer
(Zip file https://github.com/PHPMailer/PHPMailer/ … master.zip)
Extract and copy all files from src folter to /include/phpmailer/


2) Modify /include/functions_mail.inc.php

Replace lines 614 to 617:

  include_once(PHPWG_ROOT_PATH.'include/phpmailer/class.smtp.php');
  include_once(PHPWG_ROOT_PATH.'include/phpmailer/class.phpmailer.php');

  $mail = new PHPMailer;

and change by
 
  include_once(PHPWG_ROOT_PATH. 'include/phpmailer/PHPMailer.php');
  include_once(PHPWG_ROOT_PATH. 'include/phpmailer/SMTP.php');
  include_once(PHPWG_ROOT_PATH. 'include/phpmailer/Exception.php');
 
  $mail = new PHPMailer\PHPMailer\PHPMailer();
 
 
 
3) Google Setup (Applies to Google GSuite or Gmail

Enable App Password:

https://medium.com/@kumardeepak.xyz/how … c66332a017



4) Modify /local/config/config.inc.php


$conf['smtp_host'] = 'smtp.gmail.com:587';
$conf['smtp_user'] = 'ENTER YOUR GOOGLE ACCOUNT EMAIL';
$conf['smtp_password'] = 'ENTER YOUR APP PASSWORD HERE';
$conf['mail_sender_email'] = 'ENTER YOUR GOOGLE ACCOUNT EMAIL'';
$conf['mail_allow_html'] = true;
$conf['smtp_secure'] = tls;



I'm getting the following warning but at least now it works:

Warning: Cannot modify header information - headers already sent by (output started at /include/functions_mail.inc.php:937) in /include/page_header.php on line 94