Here in this article when user is sending outbound emails through sophos XG firewall he is getting “Relay not permitted error”. You can see this error under “Email >> Mail logs” by hovering over error if you are using MTA mode.
In case if you are using legacy mode, you have to login to the sophos XG firewall CLI. Then enter advanced shell, type this command “tail -f /log/smtpd_main.log” and send email.
You will be able to find the error.
First we will understand the mail flow in sophos XG for outbound emails.
Please look into the below screenshot:
First mail will be sent from mail client to mail server then mail server will use sophos XG as relay to forward emails to internet.
So we need to add mail server IP under email >> relay settings as shown below
After adding your mail server IP address, click on apply. Now you will be able to send emails.
Hope this article helps you.