Are you deploying hybrid for domain '{0}'? You have to set up a specific entry in DNS so that email delivery works as expected. ...

Are you deploying hybrid for domain '{0}'? You have to set up a specific entry in DNS so that email delivery works as expected. The missing record is type TXT.  If you're not going to use this domain for email in the cloud and email on-premises, you can just ignore this error. Click on the link 'get help fixing this issue' in the actions pane located on the right side of the screen for assistance.