Issue Error sending email

[CobraArbok]

I'm sorry, but this is my first Plesk mail service setup.
I created a mailbox and sent an email to an external address (mydomain.tld).
I received this error.

Hi. This is the qmail-send program at my-server.
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.
<name@mydomain.tld>:
Sorry, I couldn't find any host named mydomain.tld. (#5.1.2)​

 

[IgorG]

Any additional related details from /var/log/maillog ?

 

[Ales]

It could be a DNS issue or simply a fact that the domain mydomain.tld really doesn't exist.

@CobraArbok, if you login to your server's shell and execute 'dig mx mydomain.tld', what do you see?

BTW, 'dig' is a part of the 'bind-utils' package on CentOS and a part of the 'dnsutils' package on Ubuntu. If you don't have 'dig' available, just install the relevant package using your server's package manager.