I am running Smartermail 15.5 on a Windows 2012 server. I am having issues with clients sending emails out. I had them try it on there phone, desktop pc and webmail and it is very inconsistent with all sending devices. The bounce error they get is:
Failed Recipient: email@example.com
Reason: Remote host said: 550 Please turn on SMTP Authentication in your mail client.
(mail.mydomain.com) [220.127.116.11]:52355 is not permitted to relay
through this server without authentication.
My server is set to Require SMTP authentication for sending mail and when my clients here and there send out they would get this kick back. The weird thing that trips me up is I have had to customers get the bounce back even when a customer would try to send using webmail. There should be no authentication coming direct from webmail. Can someone please tell me all the different scenairos that cause this error and bounce back?
Thanks for the help in advance,