Mail servers have an SMTP authentication characteristic enabled in them, to validate customers who attempt to ship mails by way of that server.
The ‘SMTP AUTH’ error often occurs when customers attempt to ship mails with out correctly authenticating their mail account in electronic mail shoppers resembling Outlook or Thunderbird.
What causes the error ‘SMTP AUTH is required for message submission on port 587’ in cPanel/WHM servers
With the most recent cPanel/WHM replace, electronic mail ...