Nixtree Team comes across a wide range of issues to offer appropriate solutions to our clients. There was one interesting one. Our client faced the following error, while sending mail to another domain.

This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

  my_test_user@test_domain.com.au
    The mail server could not deliver mail to my_test_user@test_domain.com.au. 
The account or domain may not exist, they may be blacklisted, or missing the
proper dns entries.

The first instinct is to think the domain name does not exist or does not have a MX record. Most of this is the case. While checking mx for the domain, I noticed that the MX is pointing to an IP.

#dig MX test_domain.com.au +short
192.168.0.1

The IP address is not a valid MX record and the mailserver, which following the RFC for mail email will fail. Obviously your clients probably want mail delivered to the server even if the remote mail server is misconfigured.

To allow exim to deliver to a mail server on an IP using a misconfigured MX record address. Add the following entry in exim.conf and restart.

allow_mx_to_ip = yes

NB: dummy values are used for IP and domain.

The above scenario was a real-world example of how a problem when properly identified can be resolved to satisfy a client. Nixtree offers prompt support to all its clients to cater to their server management requirements.

Talk to our server helpdesk support experts for cPanel Server Management support requests and more. Our Nixtree experts will help is Server setups, Server Hardening, Regular patching and any other issues you may face from time to time.