554 5.7.1 : Client host rejected: Access denied

554 5.7.1 <mail-io1-f49.google.com[209.85.166.49]>: Client host rejected: Access denied

If you are running your own mailserver in a datacenter, you might have to enable the submission port (587) in postfix to be able to receive emails from the client to your own mailserver.

To enable port 587, edit the file /etc/postfix/master.cf

vi /etc/postfix/master.cf

then remove the # in front of the line:

#submission inet n - n - - smtpd

so that it looks like this:

submission inet n - n - - smtpd

then restart postfix:

/etc/init.d/postfix restart

After that please enable the submission port from your firewall too.
like :-

sudo ufw allow 587 or sudo ufw allow submission



Keep Enjoy !!!