SMTP [SMTP] Cannot send message (Sending email "Re: test " failed with error: Email recipient not accepted by the server.)

I have been trying to get my em Mail client up and running again. .as in the title. I am sure this a recurring issue but I have never found an answer.

Have you contacted your SMTP server technical support and let them know you are getting that error as I advised in your previous post below ?

Also is this error happening “with every email address you send”, or only happening with specific email addresses ?

I tried to get telstra(Australia) to help. they almost helped by suggesting I enter the operations folder and check the various points were correct.I changed the port and restarted the system and now I think it works.