I received the following NDR.
Reporting-MTA: dns;01.xx.LOCAL Final-Recipient: rfc822;email@example.com Action: failed Status: 5.5.0 Diagnostic-Code: smtp;550 bosauthsmtp08: Host xxx.xxx.xxx.xxx: No unauthenticated relaying permitted
Host: xxx.xxx.xxx.xxx is my public ip, and we don't use relay. However, I believe the user sent the email from his iphone.
Can you please let me know where I should be looking into in order to resolve this issue?
I greatly apprecaite your help and support.