Our company offers hosting, we currently have around 50 websites on our server. 3 of our customers have elected to have their email hosted on another server to help reduce spam. After changing the DNS settings for those 3 domains, we began getting failure messages when trying to send email from other domains on our server. Turns out it was a qmail issue.
Here is an example of the failure messages we were getting:
Hi. This is the qmail-send program at ip-xx.xx.xx.xxx .ip.secureserver.net.
I’m afraid I wasn’t able to deliver your message to the following addresses.
This is a permanent error; I’ve given up. Sorry it didn’t work out.
Then the email address of the recipient was followed by this line:
This address no longer accepts mail.
After googling the error, we were able to come up with a solution. Turns out, you have to remove the domains in two files and restart qmail.
To resolve the problem you have to remove the domain from /var/qmail/control/rcpthosts and /var/qmail/control/virtualdomains.
After that you have to restart the qmail by /etc/init.d/qmail restart
It worked for us!