Sender address rejected: need fully-qualified address

Help with Setup/Upgrade
1

I receive the following error.
504 5.5.2 <ECS_Notifier>: Sender address rejected: need fully-qualified address.
Test emails are supposed to be received by a gmail account
NS should be point to this email server.
This email server is on linode with a firewall set port 25 open only the server
(EDI) sending out the message
The EDI server is sending request to send on port 25.
There is no encryption. No TLS or any SSL certs.

2

If rhis is a fresh install please check propagation: https://www.whatsmydns.net/

Otherwise this error should have something to do main.cf read here:

https://serverfault.com/questions/407865/how-to-fix-postfix-sender-address-rejected-need-fully-qualified-address-in-re

Please be more specifc next time. Is evrything OK in the admin/Status page?