I have enable My outgoing server(SMTP) require authentication
I have encounter the error 554 mail server permanently rejected message (#5.3.0) can help to advise?
Hello wee and welcome to the community
Have you checked with your ISP to see if they are having an email problem. Norton doesn't usually block emails unless there is a virus in them. If you are using any other than the standard email ports, your emails aren't scanned. Usually in a case like your, NIS is acting as a messenger for your ISP. Please check with them to see if there is any problem on their end.
If everything is ok at their end, then we can continue troubleshooting. Thanks.