So in essense, I've setup info@mydomain.com.au and I access it via link above. But when sending to staff1@mydomain.com.au it bounces back, even though those emails are setup on my web server.
This is an expected behavior.
After you verify your domain name (mydomain.com.au) on Office 365, you will could use this domain name for Exchange online mailbox.
But, when you send emails to "AnuUser@mydomain.com.au", Exchange online will not send out this email to external of Exchange online, it will only search recipient within Exchange online.
For your personal mail server, user may could send email with organization. But when external user sends emails to "AnuUser@mydomain.com.au", email will be sent to Exchange online and try to find recipient on Exchange online. Because this domain name is verified on Office 365.
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