Remote server returned not permitted to relay

Hi guys,
i use a backup mail server in virtualmin. So i have

Virtualmin Pro as my main web/email server1
Virtualmin GPL as my backup mail server2

both systems run debian 9.

two issues

  1. the backup mail server will not run virtualmin updates…it cannot resolve
  2. the backup system (server2) seems to not be able to relay to the mail mail server. for example, i sent an email from hotmail to my admin account and got the following error in my hotmail account…

Your message couldn’t be delivered because an email server outside Office 365 reported an error that it couldn’t relay your message. It’s likely that the email server isn’t correctly set up to receive and relay messages from your domain. To fix this, forward this non-delivery report (NDR) message to your email admin.

I also saw a notification in mxtoolbox smtp checks that TLS is not enabled.

are these things all related? how do i fix?

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