External Mail Aliases Do Not Work

When I configure a mail alias to send to an external email address (not hosted on the Virtualmin server) the email is not sent.

An example follows:

domain1.com.au is hosted on Virtualmin.
domain2.com.au is NOT hosted on Virtualmin.

The 'accounts@domain1.com.au' is intended to redirect to 'renda@domain2.com.au'.

Error in /var/log/maillog:
Jun 21 02:10:59 web1 postfix/smtp[21648]: E75881041F7: to=renda@domain2.com.au, orig_to=domain1@istm.com.au, relay=none, delay=1, status=bounced ([primus.com.au]: Name or service not known)

I also attempted to create a new mailbox (as opposed to just an alias) and configure that to forward mail to an external email address. That also failed with the same error.

Any help with this would be greatly appreciated.


Closed (fixed)