Just don't send messages from your owner email address! I own quite a few groups. Don't think I have ever sent from there. I have received from there but its about problems or queries about the group, not the topic.
Email from the group+owner's email address doesn't appear on your group.
Use your proper login email address -?
If you don't know which is your email address - your group ID - look at the bottom of any email from Groups.io
For more info, see the wiki -?/g/GroupManagersForum/wiki/home
Frances