Mail delivery failed: returning message to sender

[feerdispzoo]

Hello,
im using WHMCS, I dont know what is this but every few secons I received ticket. Now is above 600 tickets with content:

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:

[email protected]
(ultimately generated from [email protected])
retry timeout exceeded


I dont know, what my server try send messages to server host?

 

[Richard G]

dont know, what my server try send messages to server host?

Might be returned messages, system messages or firewall messages, they are all send to root.

I would start setting a normal hostname, so oa FQDN hostname which is a domain and from which you can send mail and create rDNS/PTR record.
Because vmixxx.contaboserver.net is a contaboserver.net hostname and you don't own contabo.net domain.

So create a decent hostname like server.yourdomain.com which you can use.

To get those messages, create a redirect to root.
Edit the /etc/aliases file and on the bottom you might see something like:

# Person who should get root's mail
#root:          marc

change to:

# Person who should get root's mail
root:          [email protected]

where [email protected] is ofcourse a mail address from yourself. Then you will receive the messages and see what it's all about.